devtools: reduce test builds output size

devtools: reduce test builds output size

The various builds done by the "test-meson-builds.sh" script can take a
large amount of space on disk. Some simple changes allow us to reduce
the space used significantly. Specifically:
* use the default "release" build, which does not include debug
  information, for builds where we won't check ABI.
* use shared linkage rather than static for the 32-bit builds.

After making these changes a set of builds produced by test-meson-builds
shrank from ~17G to ~7G on my system.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>