Fix tools include path

Noticed this while working on an automated Makefile refactoring.
Extract fips/fips_standalone_sha1 rules

When the single-makefile-with-includes structure kicks in, these rules for the
same object will conflict, though they are mutually exclusive in the recursive
make structure. This change preserves the existing behavior and output; a
future change will make the inclusion of one of the .mk files or other
conditional, to avoid duplicate rules being defined.
Conditional inclusion of fips_standalone_sha1.mk

This change preserves the existing behavior and output of the existing
recursive make structure, but ensures that when the
single-makefile-with-includes structure kicks in, only one definition for the
fips/fips_standalone_sha1 target will be defined.
Migrate all_fips to conditional definition

This change preserves the same behavior and output as before, except that it
eliminates the recursive make by replacing the earlier recipe with
prerequisite targets.
Update crypto/fips to use generated rules, prereqs

This change preserves the same behavior and output as before, except that it
replaces the shell-based subdir-building recipe with generated rules and
prerequisites. This doesn't eliminate the recursive make, but refactors it so
that eliminating it will be more straightforward when the time comes.
Prefix fipsas.pl with FIPSCANISTERINTERNAL env var

This is in preparation for removing BUILDENV from Makefile.fips.
fipsdist.pl: replace BUILDENV with specific vars

This is to prepare for the elimination of the BUILDENV variable.
Set EXE_EXT explicitly for cms-test.pl

This is in anticipation of removing BUILDENV everywhere.
Remove BUILDENV after configure.mk migration

All of the Makefiles now include configure.mk, rendering BUILDENV obsolete.
Remove BUILDENV from Makefile.fips
Explicitly set EXCL_OBJ env var within ARX command