gcc: update gcc 5 to version 5.3.0

toolchain/gcc/Config.version

toolchain/gcc/common.mk

...RM-PR-target-68059-libgcc-should-not-use-__write-fo.patch

...n/gcc/patches/5.3.0/001-revert_register_mode_search.patch

toolchain/gcc/patches/5.3.0/002-case_insensitive.patch

toolchain/gcc/patches/5.3.0/010-documentation.patch

toolchain/gcc/patches/5.3.0/020-no-plt-backport.patch

...hain/gcc/patches/5.3.0/030-fix-arm-codegen-PR-65932.patch

toolchain/gcc/patches/5.3.0/040-fix-mips-ICE-PR-68400.patch

toolchain/gcc/patches/5.3.0/100-uclibc-conf.patch

toolchain/gcc/patches/5.3.0/200-musl_config.patch

toolchain/gcc/patches/5.3.0/201-musl_arm.patch

toolchain/gcc/patches/5.3.0/202-musl_mips.patch

toolchain/gcc/patches/5.3.0/203-musl_powerpc.patch

toolchain/gcc/patches/5.3.0/204-musl_sh.patch

toolchain/gcc/patches/5.3.0/205-musl_x86.patch

toolchain/gcc/patches/5.3.0/206-musl_aarch64.patch

toolchain/gcc/patches/5.3.0/207-musl_fixincludes.patch

toolchain/gcc/patches/5.3.0/209-musl_libstdc++.patch

toolchain/gcc/patches/5.3.0/230-musl_libssp.patch