Use CMAKE_INSTALL_FULL_LIBDIR/INCLUDEDIR in pkgconfig for 3.* (#1064)

This substitutes CMAKE_INSTALL_FULL_* for the hard-coded
${exec_prefix} path prefix.

Signed-off-by: Cary Phillips <cary@ilm.com>

cmake/CMakeLists.txt

@@ -183,8 +183,8 @@ if(OPENEXR_INSTALL_PKG_CONFIG)
   function(openexr_pkg_config_help pcinfile)
     set(prefix ${CMAKE_INSTALL_PREFIX})
     set(exec_prefix "\${prefix}")
-    set(libdir "\${exec_prefix}/${CMAKE_INSTALL_LIBDIR}")
-    set(includedir "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
+    set(libdir ${CMAKE_INSTALL_FULL_LIBDIR})
+    set(includedir ${CMAKE_INSTALL_FULL_INCLUDEDIR})
     string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
     set(LIB_SUFFIX_DASH ${OPENEXR_LIB_SUFFIX}${CMAKE_${uppercase_CMAKE_BUILD_TYPE}_POSTFIX})
     if(OPENEXR_ENABLE_THREADING AND TARGET Threads::Threads)