Modifies to work with gcc 4.8 for el7

[cskeeters]

This change enables parsers/scanners to work on the version of gcc that comes with el7 (RHEL7/Oracle Linux 7), which is 4.8. I assume later versions of gcc set c99 as the default standard and that's why it's not required.

The parser/scanners for most languages compile with clang 3.2.4. I set it up with this added to my init function in Lazy's configuration for treesitter.

require'nvim-treesitter.install'.compilers = { "clang" }

Unfortunately, the vim parser doesn't compile. Instead of throwing an error, it never finishes compiling. Strange; not going to investigate. For me, the best option was to use gcc and add this argument.

Would adding this argument be detrimental to compilation on newer versions of gcc? I don't know. Please don't feel obligated to take this patch. I'm just offering it and want to make it findable for anyone else having the same issue.

[clason]

Unfortunately, this will break mixed language parsers, which we still have some of.

[clason]

And I regret to say we are not interested in supporting such old compilers; it is hard enough to support current compilers on all platforms...

[clason]

But the offer is appreciated!

[ObserverOfTime]

You can set CC to a script file that passes the argument to gcc.

#!/usr/bin/sh

exec gcc --std=c99 "$@"