Jdupes 1200

[chexum]

Despite the flag ENABLE_BTRFS is enabled for make, this seems to be mishandled by the way the Makefile builds the CFLAGS, so the functionality does not get included.

(It does not depend on any BTRFS headers, libraries, or ioctls, only if the appropriate flag is given on run)

General

• This is a new package and it conforms to the quality requirements

Have the results of the proposed changes been tested?

• I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
• I generally don't use the affected packages but briefly tested this PR

Does it build and run successfully?

(Please choose at least one native build and, if supported, at least one cross build. More are better.)

• I built this PR locally for my native architecture, (x86_64-glibc)
• I built this PR locally for these architectures (if supported. mark crossbuilds):
  • aarch64-glibc
  • armv7l
  • armv6l-musl