Make testing gdb with FORCE_SEPARATE_MI_TTY=1 actually work
Runing the whole gdb testsuite with MI on a separate tty, with:
make check RUNTESTFLAGS="FORCE_SEPARATE_MI_TTY=1"
Doesn't actually work because commit 51f77c3704a6 ("Add testing
infrastruture bits for running with MI on a separate UI") included a
last-minute rename typo, now fixed with this commit.
gdb/testsuite/ChangeLog:
2016-06-30 Pedro Alves <palves@redhat.com>
* lib/mi-support.exp (default_mi_gdb_start): Declare global
FORCE_SEPARATE_MI_TTY, not SEPARATE_MI_TTY.2 files changed
