[libclang] Introduce clang_Cursor_getObjCSelectorIndex() function.

After getting a cursor with clang_getCursor for a particular source location,
allows querying the cursor in order to find out if the location points to a
selector identifier in an objc method or message expression, and which selector index it is.

rdar://11158946

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153781 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/c-index-test/c-index-test.c b/tools/c-index-test/c-index-test.c
index e774e78..8732335 100644
--- a/tools/c-index-test/c-index-test.c
+++ b/tools/c-index-test/c-index-test.c
@@ -1464,6 +1464,8 @@
           printf(")");
         }
         clang_disposeString(Spelling);
+        if (clang_Cursor_getObjCSelectorIndex(Cursor) != -1)
+          printf(" Selector index=%d",clang_Cursor_getObjCSelectorIndex(Cursor));
         if (completionString != NULL) {
           printf("\nCompletion string: ");
           print_completion_string(completionString, stdout);