[runtime] Disable KMP_HAVE_QUAD on NetBSD gcc

Disable KMP_HAVE_QUAD when building via gcc on NetBSD system,
as the build fails due to unimplemented builtins:

  .../kmp_atomic.cpp.o: In function `__kmpc_atomic_cmplx16_mul':
  .../kmp_atomic.cpp:1332: undefined reference to `__multc3'
  .../kmp_atomic.cpp.o: In function `__kmpc_atomic_cmplx16_div':
  .../kmp_atomic.cpp:1334: undefined reference to `__divtc3'
  ...

Differential Revision: https://reviews.llvm.org/D55478

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@348886 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/runtime/src/kmp_os.h b/runtime/src/kmp_os.h
index 467fd96..54daaf5 100644
--- a/runtime/src/kmp_os.h
+++ b/runtime/src/kmp_os.h
@@ -86,9 +86,12 @@
    128-bit extended precision type yet */
 typedef long double _Quad;
 #elif KMP_COMPILER_GCC
+/* GCC on NetBSD lacks __multc3/__divtc3 builtins needed for quad */
+#if !KMP_OS_NETBSD
 typedef __float128 _Quad;
 #undef KMP_HAVE_QUAD
 #define KMP_HAVE_QUAD 1
+#endif
 #elif KMP_COMPILER_MSVC
 typedef long double _Quad;
 #endif