[OpenMP] Compilation error fix on const char*

Summary:
This line
(https://github.com/llvm-mirror/openmp/blob/0ed912c7a798f5c4f65f8bb6b492e07fab7f4cea/runtime/src/kmp_gsupport.cpp#L1459)
added in D45327 (rL330282) causes a compilation failure.

Reviewers: jlpeyton

Subscribers: guansong, openmp-commits

Differential Revision: https://reviews.llvm.org/D45786

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@330299 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/runtime/src/kmp_gsupport.cpp b/runtime/src/kmp_gsupport.cpp
index c63cbda..b1923e3 100644
--- a/runtime/src/kmp_gsupport.cpp
+++ b/runtime/src/kmp_gsupport.cpp
@@ -1448,7 +1448,7 @@
   kmp_tasking_flags_t *input_flags = (kmp_tasking_flags_t *)&flags;
 #ifdef KMP_DEBUG
   {
-    const char *buff;
+    char *buff;
     buff = __kmp_str_format(
         "GOMP_taskloop: T#%%d: func:%%p data:%%p copy_func:%%p "
         "arg_size:%%ld arg_align:%%ld gomp_flags:0x%%x num_tasks:%%lu "