build/maint.mk: Comment out setting of LC_ALL
This triggers obscure bugs; really we shouldn't be overriding
the global locale here. In practice, production build systems
will be using fixed locales anyways.
Also, we only use a small subset of this file (`make syntax-check`),
which appears to work OK without this.
I will probably try to work out where to submit this as at
least an issue report for upstream gnulib.
Closes: https://github.com/ostreedev/ostree/issues/1101
Closes: #1107
Approved by: heftig