Off -fdebug-compilation-dir to generate debugsource RPM package

Make the condition which adds those flags always false for us.

// mikhailnov, 23.03.2021
--- a/build/config/compiler/BUILD.gn.orig	2021-03-14 05:19:49.661818000 +0300
+++ b/build/config/compiler/BUILD.gn	2021-03-22 21:23:36.664972000 +0300
@@ -1134,7 +1134,7 @@
   }
 
   # Makes builds independent of absolute file path.
-  if (is_clang && strip_absolute_paths_from_debug_symbols) {
+  if (is_clang && is_win) {
     # If debug option is given, clang includes $cwd in debug info by default.
     # For such build, this flag generates reproducible obj files even we use
     # different build directory like "out/feature_a" and "out/feature_b" if