CMakeDetermineCompilerId: Tolerate stray text around INFO strings

When cross-compiling with Xcode our compiler id test binary may be
compiled with multiple architectures.  The INFO strings should be
identical and therefore de-duplicated.  However, this can be broken by
stray text that happens to sit immediately before or after an INFO
string.  Filter out such text so we can match clean INFO strings.

Fixes: #21526
16 jobs for compiler-id-extra-text in 0 seconds (queued for 1 second)