[libcxx] [test] Enable gdb_pretty_printer_test.sh.cpp for clang

With current versions the CI image, this test does pass, with
both Clang 17, 18 and 19 - so there doesn't seem to be anything
Clang version specific in it.

Author: mstorsjo

libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp

@@ -11,9 +11,6 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: c++03
 
-// TODO: Investigate these failures which break the CI.
-// UNSUPPORTED: clang-17, clang-18, clang-19
-
 // The Android libc++ tests are run on a non-Android host, connected to an
 // Android device over adb. gdb needs special support to make this work (e.g.
 // gdbclient.py, ndk-gdb.py, gdbserver), and the Android organization doesn't