configure: enable pic for shared libs on AArch64

Signed-off-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -2782,7 +2782,7 @@ check_64bit(){
 }
 
 case "$arch" in
-    alpha|ia64)
+    aarch64|alpha|ia64)
         spic=$shared
     ;;
     mips)