package/dieharder: fix build with gcc 10

Disable -fno-common with dieharder, there is more than 100 variables to
fix and upstream seems dead.

Fixes:
 - http://autobuild.buildroot.org/results/ba70d111cd1f2029a193a88af3b44daf6ef27786

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/dieharder/dieharder.mk

@@ -36,4 +36,9 @@ endif
 # parallel build fail, disable it
 DIEHARDER_MAKE = $(MAKE1)
 
+# Too many fixes needed to build with -fno-common which is default since gcc 10
+ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_10),y)
+DIEHARDER_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) -fcommon"
+endif
+
 $(eval $(autotools-package))