Using `which` to check whether commands exist can result in confusing errors when `which` itself is not installed in the system. This is the case with `autoconf`, where if `autoconf` is present but `which` isn't, the build system says that `autoconf` is missing, when in reality it is `which` which is missing. The fix switches autoconf uses of `which` for `type -p` instead, which is a Bash built-in command.
I've tested the fix with a fedora docker container that had `autoconf` installed but `which`. When using `type -p` it correctly detects `autoconf` installed and eventually fails saying that `which` is not installed, which is the expected behaviour. `which` is still in use in make/autoconf/util_windows.m4. A possible future improvement would be to see if `which` use there could be replaced as well. Eventually, when no `which` uses remain, the presence check for `which` could be removed. Bug: https://bugs.openjdk.java.net/browse/JDK-8248158 WebRev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8248158/01/webrev/ Galder
