Use of -fshort-enums for certain files

[Michael Bruck]

libc/stdio/Makefile.in uses "-fshort-enums" for several files.

This causes problems with ARM targets that have this option disabled
by default. On ARM the enum format is stored as flag in the elf file
and the linker notes the discrepancy. So even if this hard-coded flag
is purely internal in these library files and affects no external
interfaces it still causes errors when linked with other objects.

Michael