[PATCH] Update configure.ac so that we don't need glibc when running ./configure.

[Flavio Cruz]

For x86_64-pc-gnu we still do not have a working glibc so ./configure will fail
under a freestanding environment. We force ./configure to avoid running
compiled C programs as a test which it is not needed when compiling a kernel.
---
 configure.ac | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/configure.ac b/configure.ac
index 3aaa935c..06a243a2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,9 @@ AC_INIT([AC_PACKAGE_NAME], [AC_PACKAGE_VERSION], 
[AC_PACKAGE_BUGREPORT],
   [AC_PACKAGE_TARNAME])
 AC_CONFIG_SRCDIR([kern/ipc_kobject.c])
 
+# We don't need glibc to compile gnumach.
+: ${CFLAGS="-ffreestanding -nostdlib"}
+
 AC_CONFIG_AUX_DIR([build-aux])
 
 AM_INIT_AUTOMAKE(
@@ -79,7 +82,12 @@ AC_SUBST([systype])
 #
 
 AC_PROG_AWK
+# Temporarily force cross compiling mode to make sure the configure script
+# does not try to run compiled binaries.
+save_cross_compiling=$cross_compiling
+cross_compiling=yes
 AM_PROG_AS
+cross_compiling=$save_cross_compiling
 AC_PROG_CC
 AC_PROG_CPP
 AC_PROG_INSTALL
-- 
2.39.0