test_build.sh: Build all programmers individually using Meson

The test build script already builds each programmer individually when
Make is used. To check if the Meson build system is working properly,
build each programmer individually and in addition to that build-test
the programmer groups individually.

Builds are done in the directory `out`, while for each build a new
subdirectory with the name of the programmer option is created.

Also, return when scan-build is used and the group `all` isn't selected,
since it's not needed to run scan-build in combination with the other
options.

Signed-off-by: Felix Singer <felixsinger@posteo.net>
Change-Id: I703127a2dc31d316d3d1c842b5bcb0b22c39c0d4
---
M test_build.sh
1 file changed, 45 insertions(+), 3 deletions(-)