gdb/testsuite/ChangeLog:
* gdb.base/watchpoint.exp (test_complex_watchpoint): Remove
compiler_info references.
* gdb.cp/temargs.exp: Ditto.
* lib/gdb.exp: Unset compiler_info instead of setting to "unknown".
(get_compiler_info): Early exit if already computed. Set compiler_info
to "unknown" if there was a problem.
(test_compiler_info): Add function comment. Call get_compiler_info.