[AIX][libc++] Enable clang_modules_include.gen.py tests

Enable these tests on AIX since they're passing.

Author: jakeegan

libcxx/test/libcxx/clang_modules_include.gen.py

@@ -30,9 +30,6 @@
 // UNSUPPORTED{BLOCKLIT}: windows
 // UNSUPPORTED{BLOCKLIT}: buildhost=windows
 
-// The AIX headers don't appear to be compatible with modules
-// UNSUPPORTED{BLOCKLIT}: LIBCXX-AIX-FIXME
-
 // The Android headers don't appear to be compatible with modules yet
 // UNSUPPORTED{BLOCKLIT}: LIBCXX-ANDROID-FIXME
 
@@ -60,9 +57,6 @@
 // UNSUPPORTED{BLOCKLIT}: windows
 // UNSUPPORTED{BLOCKLIT}: buildhost=windows
 
-// The AIX headers don't appear to be compatible with modules
-// UNSUPPORTED{BLOCKLIT}: LIBCXX-AIX-FIXME
-
 // The Android headers don't appear to be compatible with modules yet
 // UNSUPPORTED{BLOCKLIT}: LIBCXX-ANDROID-FIXME