package/libkrb5: force arm mode instead of Thumb mode

Fix the following build failure in Thumb mode:

/tmp/ccdzbA2E.s:845: Error: selected processor does not support `mcr p15,0,r2,c7,c10,5' in Thumb mode

Fixes:
 - http://autobuild.buildroot.org/results/08be1fa0fee0f05818cd78d4718caa3476c570ae

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: André Zwing <nerv@dawncrow.de>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit 355ceb893078b4e1d458a3367fc2c989911fefe1)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libkrb5/libkrb5.mk

@@ -34,6 +34,13 @@ LIBKRB5_CONF_OPTS = \
 	--without-tcl \
 	--disable-rpath
 
+# libkrb5 has some assembly function that is not present in Thumb mode:
+# Error: selected processor does not support `mcr p15,0,r2,c7,c10,5' in Thumb mode
+# so, we desactivate Thumb mode
+ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB),y)
+LIBKRB5_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) -marm"
+endif
+
 # Enabling static and shared at the same time is not supported
 ifeq ($(BR2_SHARED_STATIC_LIBS),y)
 LIBKRB5_CONF_OPTS += --disable-static