Specialize FORCE_DEFINING_FILE_TO_BE_LINKED using a GCC trick

to avoid using constructor calls for static objects. This reduces
the number of objects requiring static constructors in a typical
LLVM build by around 20%.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48665 91177308-0d34-0410-b5e6-96231b3b80d8

lib/System/IncludeFile.cpp

@@ -17,4 +17,4 @@ using namespace llvm;
 
 // This constructor is used to ensure linking of other modules. See the
 // llvm/System/IncludeFile.h header for details. 
-IncludeFile::IncludeFile(void*) {}
+IncludeFile::IncludeFile(const void*) {}