TAKE - more minor cleanup

[Steve Lord <lord@xxxxxxx>]

Put back some debug checks removed in the last mod, they are useful
for catching vm changes, remove some definitions we do not need
from elsewhere.

Date:  Mon Jan 29 12:53:50 PST 2001
Workarea:  128.162.184.86:/src/lord/xfs-linux.2.4

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.4.x-xfs


Modid:  2.4.x-xfs:slinx:83425a
linux/mm/page_alloc.c - 1.36
        - Put back debug check - ananth complained....

linux/kernel/ksyms.c - 1.71
        - Remove unused export and unneeded extern

linux/fs/buffer.c - 1.54
        - Put back debug check - ananth complained....

linux/fs/pagebuf/page_buf.c - 1.50
        - remove unneeded extern