Enable OpenMP build for 32-bit FreeBSD

Summary:
To be able to successfully build OpenMP on 32-bit FreeBSD, such as
FreeBSD/i386, I first had to provide a few wrappers (see D60916), and
then add `KMP_OS_FREEBSD` to the list of defines checked for 32-bit
architectures in `kmp_runtime.cpp`.

I have successfully built libomp.so and ran a bunch of test programs on
FreeBSD/i386 with this.

See also https://svnweb.freebsd.org/changeset/base/345283

Reviewers: emaste, jlpeyton, Hahnfeld

Reviewed By: jlpeyton

Subscribers: krytarowski, guansong, jdoerfert, openmp-commits, llvm-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D60917

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@359716 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/runtime/src/kmp_runtime.cpp b/runtime/src/kmp_runtime.cpp
index 231d168..3b636db 100644
--- a/runtime/src/kmp_runtime.cpp
+++ b/runtime/src/kmp_runtime.cpp
@@ -8256,7 +8256,7 @@
 
 #elif KMP_ARCH_X86 || KMP_ARCH_ARM || KMP_ARCH_AARCH || KMP_ARCH_MIPS
 
-#if KMP_OS_LINUX || KMP_OS_WINDOWS || KMP_OS_HURD
+#if KMP_OS_LINUX || KMP_OS_FREEBSD || KMP_OS_WINDOWS || KMP_OS_HURD
 
     // basic tuning