icu: exclude debug files from ptest execution

icu: exclude debug files from ptest execution

When EXTRA_IMAGE_FEATURES contains dbg-pkgs, a .debug directory is
created containing debug symbol files that cannot be executed, causing
ptest failures such as:

/usr/lib64/icu/ptest/run-ptest: line 7: ././.debug/cintltst: cannot execute binary file: Exec format error
FAIL: ./.debug/cintltst

Modify run-ptest script to skip .debug directory files during test
execution.

Signed-off-by: Jiaying Song <jiaying.song.cn@windriver.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>