build: impertively define output name for static library

When building with an older CMake, the generator expression is not
evaluated properly and embedded into the final output name which is
incorrect.  This should repair the ability to build with an older CMake.

src/CMakeLists.txt

@@ -98,9 +98,15 @@ if (CMARK_STATIC)
   cmark_add_compile_options(${STATICLIBRARY})
   set_target_properties(${STATICLIBRARY} PROPERTIES
     COMPILE_FLAGS -DCMARK_STATIC_DEFINE
-    OUTPUT_NAME "cmark$<$<BOOL:${MSVC}>:_static>"
     POSITION_INDEPENDENT_CODE ON
     VERSION ${PROJECT_VERSION})
+  if(MSVC)
+    set_target_properties(${STATICLIBRARY} PROPERTIES
+      OUTPUT_NAME cmark_static)
+  else()
+    set_target_properties(${STATICLIBRARY} PROPERTIES
+      OUTPUT_NAME cmark)
+  endif()
   target_include_directories(${STATICLIBRARY} INTERFACE
     $<INSTALL_INTERFACE:include>
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>