libselinux: opt-out of lto usage

libselinux: opt-out of lto usage

This fixes building with USE_LTO enabled:

<artificial>:(.text.exit+0x6e): relocation R_MIPS16_26 against `pthread_key_delete' cannot be used when making a shared object; recompile with -fPIC
./openwrt/staging_dir/toolchain-mips_24kc_gcc-12.3.0_musl/lib/gcc/mips-openwrt-linux-musl/12.3.0/../../../../mips-openwrt-linux-musl/bin/ld.bfd: non-dynamic relocations refer to dynamic symbol stpcpy
./openwrt/staging_dir/toolchain-mips_24kc_gcc-12.3.0_musl/lib/gcc/mips-openwrt-linux-musl/12.3.0/../../../../mips-openwrt-linux-musl/bin/ld.bfd: failed to set dynamic section sizes: bad value
collect2: error: ld returned 1 exit status

Signed-off-by: Anari Jalakas <anari.jalakas@gmail.com>