[cmake] Do not resolve the REALPATH too early.

In some ccache setups we have the compiler soft link to ccache.

Eg. /usr/local/bin/g++ -> /usr/local/bin/ccache. If we resolve the link too
early we will take the wrong branch assuming the compiler was set as
CMAKE_CXX_COMPILER="ccache g++" and try to get the second token of the command.

interpreter/cling/lib/Interpreter/CMakeLists.txt

@@ -128,9 +128,8 @@ if (UNIX)
 
   if(NOT CLING_CXX_PATH)
     # Remove absolute path from CMAKE_CXX_COMPILER
-    get_filename_component(_real_cxx_compiler ${CMAKE_CXX_COMPILER} REALPATH)
-    get_filename_component(_name ${_real_cxx_compiler} NAME)
-    get_filename_component(_path ${_real_cxx_compiler} PATH)
+    get_filename_component(_name ${CMAKE_CXX_COMPILER} NAME)
+    get_filename_component(_path ${CMAKE_CXX_COMPILER} PATH)
 
     # This should probably be more general...but how?
     if(_name STREQUAL "ccache" OR _name STREQUAL "distcc")
@@ -198,7 +197,11 @@ if (UNIX)
         set(_path "__THISREALLYBETTERNOTBEINPATH_THANKS__")
       endif()
     else()
-      get_filename_component(_path ${CMAKE_CXX_COMPILER} PATH)
+      # FIXME: In some ccache setups we can have a soft link pointing to ccache
+      # binary. Eg. /usr/local/gcc -> /usr/bin/ccache. Resolving the realpath
+      # we will get to the ccache and not the intended compiler binary. This
+      # could be fixed if we run 'gcc -###' which will give us the correct info.
+      get_filename_component(_path ${CMAKE_CXX_COMPILER} REALPATH)
     endif()
 
     # Test if path compiler is on PATH.