Add a C wrapper for accessing the global default context.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74675 91177308-0d34-0410-b5e6-96231b3b80d8

lib/VMCore/Core.cpp

@@ -45,6 +45,10 @@ LLVMContextRef LLVMContextCreate() {
   return wrap(new LLVMContext());
 }
 
+LLVMContextRef LLVMGetGlobalContext() {
+  return wrap(&getGlobalContext());
+}
+
 void LLVMContextDispose(LLVMContextRef C) {
   delete unwrap(C);
 }