meson: fix cross-compilation issues with gperf header file preprocessing

Pass c_args to the compiler when preprocessing the gperf header file, they might contain important bits without which compilation/preprocessing might fail (e.g. with clang on Android). cc.cmd_array() does not include the c_args and we can't easily look them up from the meson.build file, so we have to retrieve from the introspection info.

This is basically the Meson equivalent to commit 57103773.