meson: Add sha1 library options

v2: Set the define for xha1.c programatically, rather than using loads
of conditionals.
4 jobs for meson-sha1-options in 6 minutes and 25 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Docker Image
passed #846896
debian-testing

00:00:33

 
  Build And Test
passed #846897
autotools-build-and-test

00:05:51

passed #846898
meson-build-and-test

00:01:53

 
  External
passed continuous-integration/appveyor/branch