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 (closed)