(BOOT_CFLAGS): Removed.

From-SVN: r12369

gcc/config/t-linux-aout

-# The following is needed when compiling stages 2 and 3 because gcc's
-# limits.h must be picked up before /usr/include/limits.h.  This is
-# because each does an #include_next of the other if the other hasn't
-# been included. /usr/include/limits.h loses if it gets found first
-# because /usr/include is at the end of the search order.  When a
-# new version of gcc is released, gcc's limits.h hasn't been installed
-# yet and hence isn't found.
-BOOT_CFLAGS = -O $(CFLAGS) -Iinclude
-
 # Don't run fixproto
 STMP_FIXPROTO =