config.mk: remove -lc

config.mk: remove -lc

Thanks quinq!

POSIX/quinq says:

"In the absence of options that inhibit invocation of the link editor, such as
-c or -E, the c99 utility shall cause the equivalent of a -l c option to be
passed to the link editor after the last pathname operand or -l option, causing
it to be searched after all other object files and libraries are loaded."