https://www.freedesktop.org/wiki/Software/pkg-config/
https://distfiles.dereferenced.org/pkgconf/
https://ja.wikipedia.org/wiki/Pkg-config
pkg-config はすごい - あかり描像のブログ 2023
setenv PKG_CONFIG_PATH "/usr/local/gcc11/lib/pkgconfig"
/usr/local/gcc11/lib/pkgconfig/gmp.pc
prefix=/usr/local/gcc11
exec_prefix=${prefix}
includedir=${prefix}/include
libdir=${exec_prefix}/lib
Name: GNU MP
Description: GNU Multiple Precision Arithmetic Library
URL: https://gmplib.org
Version: 6.3.0
Cflags: -I${includedir}
Libs: -L${libdir} -lgmp
