c-index-test.c: Fix a comment style. /* It is C source. */

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144274 91177308-0d34-0410-b5e6-96231b3b80d8

tools/c-index-test/c-index-test.c

@@ -2552,7 +2552,7 @@ static void printDiagnosticSet(CXDiagnosticSet Diags, unsigned indent) {
     printRanges(D, indent);
     printFixIts(D, indent);
     
-    // Print subdiagnostics.
+    /* Print subdiagnostics. */
     printDiagnosticSet(clang_getChildDiagnostics(D), indent+2);
 
     clang_disposeString(FileName);