use the correct program to determine if a program exists; type -P

We are a bash script, so type -P does precisely what people think they
want `which` to do. Except `which` doesn't exist on my system! And in
general it is non-portable -- it has many different implementations,
some of which don't return failure on failures, and others of which
don't actually, erm, check $PATH (looking at you, ~/.cshrc `which`).

Author: eli-schwartz

build_win32.sh

@@ -24,7 +24,7 @@ check_programs() {
   local i errors
   errors=0
   for i in "${REQUIRED[@]}"; do
-    which $i &> /dev/null || error "Missing program $i"
+    type -P $i &> /dev/null || error "Missing program $i"
   done
   exit_on_error
 }