build: fix stray debug string in LIEF defines

A stray debug string 'testtttt' in lief.gyp's defines list was missing
a trailing comma, causing it to be concatenated with the adjacent
MBEDTLS_CONFIG_FILE define via implicit string concatenation. This
resulted in the compiler receiving:

  -DtestttttMBEDTLS_CONFIG_FILE="config/mbedtls/config.h"

instead of:

  -DMBEDTLS_CONFIG_FILE="config/mbedtls/config.h"

Remove the stray string so that MBEDTLS_CONFIG_FILE is defined
correctly.

Refs: #62129
PR-URL: #62683
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Richard Lau <richard.lau@ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: om-ghante

deps/LIEF/lief.gyp

@@ -443,7 +443,6 @@
       },
       'defines': [
         'LIEF_STATIC',
-        'testtttt'
         'MBEDTLS_CONFIG_FILE="config/mbedtls/config.h"',
         'MBEDTLS_NO_PLATFORM_ENTROPY',
         'SPDLOG_DISABLE_DEFAULT_LOGGER',