[LLVM-C] Add bindings to create enumerators

[Jiboo]

Summary

The C API don't have the bindings to create enumerators, needed to create an enumeration.

[whitequark]

LGTM

[CodaFi]

I concur. Looks good.

[harlanhaskins]

Thanks!

[Jiboo]

It seem to also miss macro related bindings, I'll probably make another differential today.

I don't have commit rights, I'd be glad if someone could commit this.

[CodaFi]

I keep a running list of the APIs we have wrapped if that helps. I would love a hand getting us all the way there https://github.com/llvm-swift/LLVMSwift/issues/131

llvm/trunk/include/llvm-c/DebugInfo.h

 LLVMMetadataRef
 LLVMDIBuilderCreateSubroutineType(LLVMDIBuilderRef Builder,
                                   LLVMMetadataRef File,
                                   LLVMMetadataRef *ParameterTypes,
                                   unsigned NumParameterTypes,
                                   LLVMDIFlags Flags);
 
 /**
+ * Create debugging information entry for an enumerator.
+ * @param Builder        The DIBuilder.
+ * @param Name           Enumerator name.
+ * @param NameLen        Length of enumerator name.
+ * @param Value          Enumerator value.
+ * @param IsUnsigned     True if the value is unsigned.
+ */
+LLVMMetadataRef LLVMDIBuilderCreateEnumerator(LLVMDIBuilderRef Builder,
+                                              const char *Name, size_t NameLen,
+                                              int64_t Value,
+                                              LLVMBool IsUnsigned);
+
+/**
  * Create debugging information entry for an enumeration.
  * \param Builder        The DIBuilder.
  * \param Scope          Scope in which this enumeration is defined.
  * \param Name           Enumeration name.
  * \param NameLen        Length of enumeration name.
  * \param File           File where this member is defined.
  * \param LineNumber     Line number.
  * \param SizeInBits     Member size.

llvm/trunk/lib/IR/DebugInfo.cpp

 unsigned LLVMDILocationGetColumn(LLVMMetadataRef Location) {
   return unwrapDI<DILocation>(Location)->getColumn();
 }
 
 LLVMMetadataRef LLVMDILocationGetScope(LLVMMetadataRef Location) {
   return wrap(unwrapDI<DILocation>(Location)->getScope());
 }
 
+LLVMMetadataRef LLVMDIBuilderCreateEnumerator(LLVMDIBuilderRef Builder,
+                                              const char *Name, size_t NameLen,
+                                              int64_t Value,
+                                              LLVMBool IsUnsigned) {
+  return wrap(unwrap(Builder)->createEnumerator({Name, NameLen}, Value,
+                                                IsUnsigned != 0));
+}
+
 LLVMMetadataRef LLVMDIBuilderCreateEnumerationType(
   LLVMDIBuilderRef Builder, LLVMMetadataRef Scope, const char *Name,
   size_t NameLen, LLVMMetadataRef File, unsigned LineNumber,
   uint64_t SizeInBits, uint32_t AlignInBits, LLVMMetadataRef *Elements,
   unsigned NumElements, LLVMMetadataRef ClassTy) {
 auto Elts = unwrap(Builder)->getOrCreateArray({unwrap(Elements),
                                                NumElements});
 return wrap(unwrap(Builder)->createEnumerationType(