configure: break a long line

Originally committed as revision 20108 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -2163,7 +2163,8 @@ elif enabled x86; then
 EOF
 
     # check whether EBX is available on x86
-    check_asm ebx_available '""::"b"(0)' && check_asm ebx_available '"":::"%ebx"'
+    check_asm ebx_available '""::"b"(0)' &&
+        check_asm ebx_available '"":::"%ebx"'
 
     # check whether more than 10 operands are supported
     check_cc <<EOF && enable ten_operands