Check for more warnings in configure logs

[ryandesign]

Check for -Wimplicit-int and -Wincompatible-function-pointer-types warnings in configure logs because llvm.org clang 16 and the latest Apple clang consider those to be errors.

Closes: https://trac.macports.org/ticket/70017

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This is an initial attempt that works but it could possibly be improved. There is some code duplication with the implicit function declaration checks. And since function names are not involved in these warnings, no information other than the configuration log file the warning appeared in is shown. Maybe showing how many occurrences were found in each log file would be useful, though that improvement might also be helpful in the implicit function declaration checks.