[ASan] [Windows] Remove const from _msize function declaration parameter

This function isn't declared with a const parameter anywhere; neither
in MSVC (neither in ucrt or in older msvcrt versions) nor in mingw-w64.

Differential Revision: https://reviews.llvm.org/D51876

llvm-svn: 341903

compiler-rt/lib/asan/asan_malloc_win.cc

@@ -125,7 +125,7 @@ void *_recalloc_base(void *p, size_t n, size_t elem_size) {
 }
 
 ALLOCATION_FUNCTION_ATTRIBUTE
-size_t _msize(const void *ptr) {
+size_t _msize(void *ptr) {
   GET_CURRENT_PC_BP_SP;
   (void)sp;
   return asan_malloc_usable_size(ptr, pc, bp);