i386: Use TESTB instead of TESTL in ____longjmp_chk()

i386: Use TESTB instead of TESTL in ____longjmp_chk()

There is no need to use TESTL when checking the least-significant bit
with a TEST instruction. Use TESTB, which is three bytes shorter:

   f6 44 24 04 01          testb  $0x1,0x4(%esp)

vs:

   f7 44 24 04 01 00 00    testl  $0x1,0x4(%esp)
   00

for the same effect.

No functional changes intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: H.J.Lu <hjl.tools@gmail.com>
Cc: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>