Support appending flags

[isuruf]

In other build systems, a user can give a set of flags that are appended to the default set of flags.
fpm build --flag <flags> overrides the defaults which is not what I want.

Also, it'd be great if this was supported as an environment flag FFLAGS which would make fpm
behave like every other build system. (CMake, autoconf, setuptools, meson, etc)

[awvwgk]

To retain the defaults you can specify the profile you want to append your flags to

fpm build --profile release --flag <flag>

Reading from FFLAGS automatically would be nice, but we are also ignoring FC right now and use our own FPM_COMPILER variable instead.

[isuruf]

Thanks @awvwgk. If I have a set of flags in FFLAGS, I can't pass them like fpm build --profile release --flag $FFLAGS right? Is there a way to send in multiple without specifying --flag multiple times?

[awvwgk]

I don't see why

fpm build --profile release --flag "$FFLAGS"

wouldn't work for this purpose.

[awvwgk]

We are actually using this already for bootstrapping:

fpm/install.sh

Line 69 in 6d9004d

$BOOTSTRAP_DIR/fpm install --compiler "$FC" --flag "$FFLAGS" --prefix "$PREFIX"

[isuruf]

That's great. Thanks.