[AIX][ZOS] Excluding merge-objc-interface.m from Tests

Objective C is not supported on AIX or ZOS. This patch excludes the newly added `clang/test/Modules/merge-objc-interface.m` (added by https://reviews.llvm.org/D110280) from AIX and ZOS testing.

Many existing tests are already disabled by https://reviews.llvm.org/D109060.

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D111406

clang/test/Modules/merge-objc-interface.m

@@ -1,3 +1,4 @@
+// UNSUPPORTED: -zos, -aix
 // RUN: rm -rf %t
 // RUN: split-file %s %t
 // RUN: %clang_cc1 -emit-llvm -o %t/test.bc -F%t/Frameworks %t/test.m \