Fix #4799: Use Meson to set `c_std=c99` #19756

Job	Run time
Build on CentOS 7	10m 31s
changes	5s
Build on gcc 11 ASAN	56m 13s
Build on old Debian debian:wheezy	13m 15s
Build on old Debian debian:jessie	13m 11s
Run debug tests on Ubuntu 20.04	9m 30s
Build on old Debian debian:stretch	13m 21s
Build static	15m 55s
Create source tarball	1m 31s
linux-meson-clang-tests	2s
linux-meson-gcc-tests	21m 35s
macos-meson-clang-tests	12m 55s
linux-gcc-tests-asan	1h 3m 23s
linux-clang-tests-asan	49m 56s
linux-gcc-tests-codecov	1s
capstone-v4	1s
capstone-v5	1s
capstone-sys	4s
no-gpl-code	2s
Test source tarball	2m 55s
Build rizin rzpipe	2m 58s
Build rz-bindgen	3m 29s
Build Android ${{ matrix.name }} package	0s
Build OSX package	0s
Build Windows zip/installer ${{ matrix.name }}	0s
Include Rizin headers from C++ program (Linux)	0s
Test EXTRA_PREFIX works well	0s
Test use as meson subproject	0s
Publish Docker image on Docker Hub	0s
Test OSX pkg	0s
Test Windows installer built with ${{ matrix.name }}	0s
Create draft release and upload artifacts	0s
	4h 50m 54s

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