Don't require an absolute path for the install command.

--- build-tools/icon-theme-installer.orig	Sun Apr  4 23:09:29 2010
+++ build-tools/icon-theme-installer	Sun Apr  4 23:10:06 2010
@@ -103,12 +103,12 @@ if test -z "$INSTALL_BASE_DIR"; then
 	exit 1
 fi
 
-if test ! -x `echo "$MKINSTALLDIRS_EXEC" | cut -f1 -d' '`; then
+if test -z "$MKINSTALLDIRS_EXEC"; then
 	echo "Cannot find '$MKINSTALLDIRS_EXEC'; You probably want to pass -m \$(mkinstalldirs)"
 	exit 1
 fi
 
-if test ! -x `echo "$INSTALL_DATA_EXEC" | cut -f1 -d' '`; then
+if test -z "$INSTALL_DATA_EXEC"; then
 	echo "Cannot find '$INSTALL_DATA_EXEC'; You probably want to pass -x \$(INSTALL_DATA)"
 	exit 1
 fi
