[binutils-gdb] Fix constness problem in ioscm_make_gdb_stdio_port

[sergiodj+buildbot at redhat dot com]

*** TEST RESULTS FOR COMMIT 48ffa2b8cd986527a41654c3b27755bbf6762048 ***

Author: Simon Marchi <simon.marchi@polymtl.ca>
Branch: master
Commit: 48ffa2b8cd986527a41654c3b27755bbf6762048

Fix constness problem in ioscm_make_gdb_stdio_port

ioscm_make_gdb_stdio_port passes const char pointers (literal strings) to
scm_mode_bits, which takes a non-const char pointer.  Ideally, we would
change scm_mode_bits to take a const char pointer, but it's not part of
an API we control.

Instead, it's easy enough to build the string to pass to scm_mode_bits in
a (non-const) char array and pass that.

gdb/ChangeLog:

	* guile/scm-ports.c (ioscm_make_gdb_stdio_port): Pass non-const
	char pointer to scm_mode_bits.