Add support for string attributes in the C API.

Summary: As per title. This completes the C API Attribute support.

Reviewers: Wallbraker, whitequark, echristo, rafael, jyknight

Subscribers: mehdi_amini

Differential Revision: http://reviews.llvm.org/D21365

llvm-svn: 272811
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index b71e1ba..07b2115 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -390,6 +390,12 @@
   setAttributes(PAL);
 }
 
+void Function::removeAttribute(unsigned i, StringRef Kind) {
+  AttributeSet PAL = getAttributes();
+  PAL = PAL.removeAttribute(getContext(), i, Kind);
+  setAttributes(PAL);
+}
+
 void Function::removeAttributes(unsigned i, AttributeSet Attrs) {
   AttributeSet PAL = getAttributes();
   PAL = PAL.removeAttributes(getContext(), i, Attrs);