testsuite, jit: Stabilize error output.

Currently when a test fails, we print out a lot of information,
this includes items that are not stable between invocations (e.g.
the PID for the executable).  That makes automated comparisons
between test runs flag any persistent fails as new ones each time
which is not usually what is wanted.

This patch amends the error output to drop the variable portion
of the message and retain items that should only change if the
failure mode changes.

gcc/testsuite/ChangeLog:

	* jit.dg/jit.exp: Filter error output to remove per-run
	variable content.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>