Set PHP_CONFIG_FILE_PATH to CMAKE_INSTALL_SYSCONFDIR

This is still annoyingly buggy and not resolved properly yet but this
can be set to either absolute or relative path now already.

Author: petk

cmake/cmake/Configuration.cmake

@@ -110,10 +110,9 @@ if(NOT CMAKE_SYSTEM_NAME STREQUAL "Windows")
   )
   mark_as_advanced(PHP_CONFIG_FILE_PATH)
   if(NOT PHP_CONFIG_FILE_PATH)
-    # TODO: Fix this for the 'cmake --install ... --prefix' case.
     set_property(
       CACHE PHP_CONFIG_FILE_PATH
-      PROPERTY VALUE "${CMAKE_INSTALL_FULL_SYSCONFDIR}"
+      PROPERTY VALUE "${CMAKE_INSTALL_SYSCONFDIR}"
     )
   endif()
 endif()