gcc-testsuite: Fix test failures with output pattern due to ssh warning.

gcc-testsuite: Fix test failures with output pattern due to ssh warning.

when running oe-selftest for gcc some of the output pattern matchng test cases
were getting failed due to below issue.

Output line 1 was:
Warning: Permanently added '192.168.7
Should match (from /poky/poky/build-st/tmp/work-shared/gcc-15.1.0-r0/sources/
gcc-15.1.0/gcc/testsuite/gcc.dg/dg-output-file-1-lp64.txt):
This is a test output for lp64 target
Failed test for output line 1 This is a test output for lp64 target

Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>