vars/build.vars:host_toolchain_deps:${PKG_PREFIX}: set to ${PREFIX}.
    vars/build.vars:mpfr_host:${PKG_CONFIGURE_ARGS_EXTRA}: configure w/ --with-gmp=${PREFIX}.
    vars/build.vars:mpc_host:${PKG_CONFIGURE_ARGS_EXTRA}: configure w/ --with-gmp=${PREFIX} --with-mpfr=${PREFIX}.
    vars/build.vars:psxtypes_host:${PKG_PREFIX}: override w/ ${PREFIX_CROSS}.
    vars/build.vars:gcc_stage1_host:${PKG_CFLAGS_CONFIGURE}: configure w/ -I${PREFIX}/include.
    vars/build.vars:gcc_stage1_host:${PKG_LDFLAGS_CONFIGURE}: configure w/ -Wl,-rpath,${PREFIX_CROSS}/lib.
    vars/gcc.vars:pkgp_gcc_setup_env(): pass ${LDFLAGS} from ${PKG_LDFLAGS_CONFIGURE}.
    vars/gcc.vars:pkg_gcc_stage1_{cross,native}_mingw32_all(): correctly mkdir w/ ex_rtl_fileop.
    vars/gcc.vars:pkg_gcc_stage1_all(): pass --with-{gmp,mpc,mpfr}="${PREFIX}".