Properly nest AC_MSG_CHECKING and AC_MSG_RESULT calls to avoid confusing output.
Fix typo from 859866a.
Replace '\0' with NULL as char* argument, avoiding warning.
Revert unintended restoration of AC_MSG_RESULT.
Merge remote-tracking branch 'upstream/master'
More '\0' -> NULL replacements to avoid clang warnings
Disable non-literal-null-conversion warning issued by clang
Merge remote-tracking branch 'upstream/master'