Bug 665272 - Require unzip during configure, r=ted

configure.in

@@ -982,7 +982,10 @@ AC_SUBST(NSINSTALL_BIN)
 
 MOZ_PATH_PROG(DOXYGEN, doxygen, :)
 MOZ_PATH_PROG(AUTOCONF, autoconf, :)
-MOZ_PATH_PROG(UNZIP, unzip, :)
+MOZ_PATH_PROGS(UNZIP, unzip)
+if test -z "$UNZIP" -o "$UNZIP" = ":"; then
+    AC_MSG_ERROR([unzip not found in \$PATH])
+fi
 MOZ_PATH_PROGS(ZIP, zip)
 if test -z "$ZIP" -o "$ZIP" = ":"; then
     AC_MSG_ERROR([zip not found in \$PATH])