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.
Akira TAGOH
Tim-Philipp Müller