Fails to build liberasurecode when CC=gcc

[koba-e964]

On MacOS, if gcc is installed, CC=gcc cargo build or simply cargo build fails with the error log like below:
https://gist.github.com/koba-e964/c9ff5ab39b0ef510d0a893af54f4c0a4

Probably this is because of adding an option -Wno-error=address-of-packed-member here, which is valid in clang but not in gcc.

liberasurecode/install_deps.sh

Lines 44 to 46 in c853227

	if [ "$(uname)" == "Darwin" ]; then
	CFLAGS="$CFLAGS -Wno-error=address-of-packed-member"
	fi

Fixing this should be easy. Should I do this?

[yuezato]

Thank you for your detailed report! Instead of you, I'm working on this problem.

I can reproduce this problem on my Mac 10.13.6 as follows:

$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.13.6
BuildVersion:	17G5019

$ /usr/local/bin/gcc-8 --version # I installed gcc by `brew install gcc`
gcc-8 (Homebrew GCC 8.3.0) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ CC=/usr/local/bin/gcc-8 cargo build
   Compiling libc v0.2.51
   Compiling liberasurecode v1.0.2 (/Users/uezato/frugalos/liberasurecode)
error: failed to run custom build command for `liberasurecode v1.0.2 (/Users/uezato/frugalos/liberasurecode)`
process didn't exit successfully: `/Users/uezato/frugalos/liberasurecode/target/debug/build/liberasurecode-03e82565d13e637a/build-script-build` (exit code: 101)
...

$ grep "address-of-packed-member" ./target/debug/build/liberasurecode-8278567ad8c5b89e/out/build/liberasurecode/config.log
cc1: error: -Werror=address-of-packed-member: no option -Waddress-of-packed-member