gas-preprocessor: support .bss

same as .data on Mach-O it seems

Author: notaz

tools/gas-preprocessor.pl

@@ -121,6 +121,7 @@
     s/\.global/.globl/x;
     # also catch .section .rodata since the equivalent to .const_data is .section __DATA,__const
     s/(.*)\.rodata/.const_data/x;
+    s/\.bss/.data/x;
     s/\.int/.long/x;
     s/\.float/.single/x;