Don't include alloca.h on FreeBSD.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6728 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 0b7ad64..3dfd8f9 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -528,7 +528,9 @@
       << "extern void *__builtin_alloca(unsigned long);\n"
       << "#define alloca(x) __builtin_alloca(x)\n"
       << "#else\n"
+      << "#ifndef __FreeBSD__\n"
       << "#include <alloca.h>\n"
+      << "#endif\n"
       << "#endif\n\n";
 }