Added the -fPIC flag to the supported pch flags

PrecompiledHeader.cmake

@@ -65,6 +65,7 @@ endmacro()
 
 function(export_all_flags _filename mode)
   set(_include_directories "$<TARGET_PROPERTY:${_target},INCLUDE_DIRECTORIES>")
+  set(_pic "$<$<BOOL:$<TARGET_PROPERTY:${_target},POSITION_INDEPENDENT_CODE>>:-fPIC\n>")
   set(_compile_definitions "$<TARGET_PROPERTY:${_target},COMPILE_DEFINITIONS>")
   set(_compile_flags "$<TARGET_PROPERTY:${_target},COMPILE_FLAGS>")
   set(_compile_options "$<TARGET_PROPERTY:${_target},COMPILE_OPTIONS>")
@@ -98,8 +99,9 @@ function(export_all_flags _filename mode)
     set(_standard_check "${_standard_check}$<$<AND:$<STREQUAL:${_c_standard},99>,${_has_extensions}>:${CMAKE_C99_EXTENSION_COMPILE_OPTION}>")
     set(_standard_check "${_standard_check}$<$<AND:$<STREQUAL:${_c_standard},90>,${_has_extensions}>:${CMAKE_C90_EXTENSION_COMPILE_OPTION}>")
   endif()
+  set(_standard_check "${_standard_check}\n")
 
-  file(GENERATE OUTPUT "${_filename}" CONTENT "${_compile_definitions}${_include_directories}${_compile_flags}${_compile_options}${_standard_check}\n")
+  file(GENERATE OUTPUT "${_filename}" CONTENT "${_compile_definitions}${_include_directories}${_compile_flags}${_compile_options}${_standard_check}${_pic}\n")
 endfunction()
 
 function (gcc_pch_targets_for_mode _input _pch_path mode)