[build] ShowProjectConfig CMake Module.

[jlsantiago0]

Implement a CMakeModule that can be used to Print the SRT Project Configuration and enable it by default:

Example:

========================================================================
= Project Configuration:
========================================================================
  SRT Version:
    SRT_VERSION: 1.4.4
    SRT_VERSION_BUILD: 
  CMake Configuration:
    CMAKE_VERSION: 3.16.3
    CMAKE_INSTALL_PREFIX: /mnt/jlsws0/dev/orthrus/master/src/vendor/utils/haisrt/tt/bb22/stage
    CMAKE_BUILD_TYPE: Release
  Target Configuration:
    CMAKE_SYSTEM_NAME: Linux
    CMAKE_SYSTEM_VERSION: 5.11.0-34-generic
    CMAKE_SYSTEM_PROCESSOR: x86_64
    CMAKE_SIZEOF_VOID_P: 8
    DARWIN: 0
    LINUX: 1
    BSD: 0
    MICROSOFT: 0
    GNU: 0
    ANDROID: 0
    SUNOS: 0
    POSIX: 1
    SYMLINKABLE: 1
    APPLE: 
    UNIX: 1
    WIN32: 
    MINGW: 
    CYGWIN: 
    CYGWIN_USE_POSIX: OFF
  Toolchain Configuration:
    CMAKE_TOOLCHAIN_FILE: 
    CMAKE_CROSSCOMPILING: FALSE
    CMAKE_C_COMPILER_ID: GNU
    CMAKE_C_COMPILER_VERSION: 9.3.0
    CMAKE_C_COMPILER: /usr/bin/cc
    CMAKE_C_COMPILE_FEATURES: c_std_90;c_function_prototypes;c_std_99;c_restrict;c_variadic_macros;c_std_11;c_static_assert
    CMAKE_C_STANDARD: 
    CMAKE_CXX_COMPILER_ID: GNU
    CMAKE_CXX_COMPILER_VERSION: 9.3.0
    CMAKE_CXX_COMPILER: /usr/bin/c++
    CMAKE_CXX_COMPILE_FEATURES: cxx_std_98;cxx_template_template_parameters;cxx_std_11;cxx_alias_templates;cxx_alignas;cxx_alignof;cxx_attributes;cxx_auto_type;cxx_constexpr;cxx_decltype;cxx_decltype_incomplete_return_types;cxx_default_function_template_args;cxx_defaulted_functions;cxx_defaulted_move_initializers;cxx_delegating_constructors;cxx_deleted_functions;cxx_enum_forward_declarations;cxx_explicit_conversions;cxx_extended_friend_declarations;cxx_extern_templates;cxx_final;cxx_func_identifier;cxx_generalized_initializers;cxx_inheriting_constructors;cxx_inline_namespaces;cxx_lambdas;cxx_local_type_template_args;cxx_long_long_type;cxx_noexcept;cxx_nonstatic_member_init;cxx_nullptr;cxx_override;cxx_range_for;cxx_raw_string_literals;cxx_reference_qualified_functions;cxx_right_angle_brackets;cxx_rvalue_references;cxx_sizeof_member;cxx_static_assert;cxx_strong_enums;cxx_thread_local;cxx_trailing_return_types;cxx_unicode_literals;cxx_uniform_initialization;cxx_unrestricted_unions;cxx_user_literals;cxx_variadic_macros;cxx_variadic_templates;cxx_std_14;cxx_aggregate_default_initializers;cxx_attribute_deprecated;cxx_binary_literals;cxx_contextual_conversions;cxx_decltype_auto;cxx_digit_separators;cxx_generic_lambdas;cxx_lambda_init_captures;cxx_relaxed_constexpr;cxx_return_type_deduction;cxx_variable_templates;cxx_std_17;cxx_std_20
    CMAKE_CXX_STANDARD: 
    CMAKE_LINKER: /usr/bin/ld
    CMAKE_NM: /usr/bin/nm
    CMAKE_AR: /usr/bin/ar
    CMAKE_RANLIB: /usr/bin/ranlib
    HAVE_COMPILER_GNU_COMPAT: 1
    CMAKE_THREAD_LIBS: 
    CMAKE_THREAD_LIBS_INIT: -lpthread
    ENABLE_THREAD_CHECK: 
    USE_CXX_STD_APP: 
    USE_CXX_STD_LIB: 
    STDCXX: 
    USE_CXX_STD: 
    HAVE_CLOCK_GETTIME_IN: 1
    HAVE_CLOCK_GETTIME_LIBRT: 
    HAVE_PTHREAD_GETNAME_NP_IN_PTHREAD_NP_H: 
    HAVE_PTHREAD_SETNAME_NP_IN_PTHREAD_NP_H: 
    HAVE_PTHREAD_GETNAME_NP: 1
    HAVE_PTHREAD_SETNAME_NP: 1
    HAVE_LIBATOMIC: 1
    HAVE_LIBATOMIC_COMPILES: 1
    HAVE_LIBATOMIC_COMPILES_STATIC: 1
    HAVE_GCCATOMIC_INTRINSICS: 1
    HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC: 
    HAVE_CXX_ATOMIC: 1
    HAVE_CXX_ATOMIC_STATIC: 1
  Project Configuration:
    ENABLE_DEBUG: OFF
    ENABLE_CXX11: ON
    ENABLE_APPS: ON
    ENABLE_EXPERIMENTAL_BONDING: OFF
    ENABLE_TESTING: OFF
    ENABLE_PROFILE: OFF
    ENABLE_LOGGING: ON
    ENABLE_HEAVY_LOGGING: OFF
    ENABLE_HAICRYPT_LOGGING: OFF
    ENABLE_SHARED: ON
    ENABLE_STATIC: ON
    ENABLE_RELATIVE_LIBPATH: OFF
    ENABLE_GETNAMEINFO: OFF
    ENABLE_UNITTESTS: OFF
    ENABLE_ENCRYPTION: ON
    ENABLE_CXX_DEPS: ON
    USE_STATIC_LIBSTDCXX: OFF
    ENABLE_INET_PTON: ON
    ENABLE_CODE_COVERAGE: OFF
    ENABLE_MONOTONIC_CLOCK: ON
    ENABLE_STDCXX_SYNC: OFF
    USE_OPENSSL_PC: ON
    USE_BUSY_WAITING: OFF
    USE_GNUSTL: OFF
    ENABLE_SOCK_CLOEXEC: ON
    ENABLE_SHOW_PROJECT_CONFIG: ON
    ENABLE_CLANG_TSA: OFF
    ATOMIC_USE_SRT_SYNC_MUTEX: OFF
  Constructed Configuration:
    DISABLE_CXX11: 
    USE_ENCLIB: openssl
    ENABLE_EXAMPLES: 
    TARGET_srt: srt
    srt_libspec_static: ON
    srt_libspec_shared: ON
    Target Link Libraries:
      Static: ssl;crypto;-lpthread;atomic
      Shared: ssl;crypto;-lpthread
========================================================================

[maxsharabayko]

Please also add the new option (ENABLE_SHOW_PROJECT_CONFIG) to the "build options" documentation.
The document describes build option of the ./configure script instead of CMake build option directly.
However, the document will likelyl be used as a base for the proper documentation of SRT CMake build options.

Please note, configure scriptexpects--enable-show-project-configoption, and it will automatically convert it to CMake format ofENABLE_SHOW_PROJECT_CONFIG`.

[maxsharabayko]

I would make such verbose output off by default.