patch for .SHELLFLAGS and .POSIX

[David Boyce]

The attached little patch appears to add the .SHELLFLAGS feature with
.POSIX interaction as previously discussed:

% cat MF
.PHONY: all
.POSIX:
all:
        @echo SHELLFLAGS=$(.SHELLFLAGS)
        @false; echo NOT POSIX BEHAVIOR

% ./make -f MF
SHELLFLAGS=-ec
make: *** [all] Error 255

Please let me know if and where it falls short.

Thanks,
-DSB

shellflags.patch.gz
Description: GNU Zip compressed data