bootstrap/7237: HP/UX 10.20 compile problems, e.g, STAGE1_CFLAGS not overriden

[John David Anglin]

It is very tricky to redefine STAGE1_CFLAGS.  The best way to do the
initial build using the HP ansi compiler is to export CC as follows:

export CC="cc -Ae"

or for a 64-bit build under HP-UX 11,

export CC="cc -Ae +DA2.0W"

This should be done before configure is run.  Don't mess with
CFLAGS, STAGE1_CFLAGS or BOOT_CFLAGS.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7237