botan: fix static build

Don't pass crs in AR as it is now done by botan, see:
https://github.com/randombit/botan/commit/a9e4eede3942748234d705cc616ecc106e3767a6

Fixes:
 - http://autobuild.buildroot.org/results/5c15fe739cb1b6079dacf234699ee048924b74fb

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/botan/botan.mk

@@ -87,7 +87,7 @@ define BOTAN_CONFIGURE_CMDS
 endef
 
 define BOTAN_BUILD_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) AR="$(TARGET_AR) crs"
+	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) AR="$(TARGET_AR)"
 endef
 
 define BOTAN_INSTALL_STAGING_CMDS