This change takes the idea of handling strings as pairs in the form
(start, len) by Robert Elz from
https://mail-index.netbsd.org/source-changes-d/2021/08/20/msg013427.html
and expands it by avoiding one more memory allocation, for iterating the
PATH environment variable.
No functional change.
Previously, findcc modified its argument string, even though it had been
declared as 'const char *'. This triggered a lint warning that "strchr
effectively discards 'const char *' from argument", in fact, this code
caused the lint check to be implemented in the first place.
The first attempt at fixing it by removing the 'const' from the
parameter type was a bad idea since it made the API of that function
more complicated.
Revert back to making the parameter a 'const char *' and duplicate that
string internally as necessary. Add a few more tests for absolute
pathnames since these had been missing before. There are no tests yet
for snprintf with too long strings, but the current change does not
modify that part of the code.
rillig