OpenWrt (modification):
Fix cross compile errors by inserting an environment variable for the
target. Use "uname" on host only if "UNAME" variable is empty.
--- a/configure.ac
+++ b/configure.ac
@@ -812,7 +812,7 @@ if test x_$ub_test_python != x_no; then
    fi
 fi
 
-if test "`uname`" = "NetBSD"; then
+if test "${UNAME:-`uname`}" = "NetBSD"; then
 	NETBSD_LINTFLAGS='"-D__RENAME(x)=" -D_NETINET_IN_H_'
 	AC_SUBST(NETBSD_LINTFLAGS)
 fi