Only include scmrev.h from Version.cpp.

This way less code has to be rebuilt whenever that file gets
regenerated.

Source/Core/Common/Src/Common.h

@@ -13,7 +13,10 @@
 #include <string.h>
 
 // SVN version number
+extern const char *scm_desc_str;
+extern const char *scm_branch_str;
 extern const char *scm_rev_str;
+extern const char *scm_rev_git_str;
 extern const char *netplay_dolphin_ver;
 
 // Force enable logging in the right modes. For some reason, something had changed