meson: Add optimisation level s and disable debug in meson build

Makefile has optimisation level set explicitly. This patch
sets the same level s into meson build.

Also disable debug by default to correspond to make builds.

These two options (optimisation and debug) are linked together
in meson build, so they need to be set together to be properly
recognised for builds.

Alternative approach would be to use buildtype option (and do not
set optimisation and debug). However, none of the standard
buildtypes gives a combination that we need:
optimisation level s and debug disabled.

Tested: ninja test shows no warnings and tests pass

Change-Id: I4ca96a866529cac320e66516ef280d5100ceefab
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/63606
Original-Reviewed-by: Thomas Heijligen <src@posteo.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72325
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/meson.build b/meson.build
index 2db7299..3778f4d 100644
--- a/meson.build
+++ b/meson.build
@@ -2,7 +2,11 @@
   version : run_command('util/getversion.sh', '--version').stdout().strip(),
   license : 'GPL-2.0',
   meson_version : '>=0.50.0',
-  default_options : ['warning_level=2', 'c_std=c99'],
+  default_options : [
+    'warning_level=2',
+    'c_std=c99',
+    'optimization=s',
+    'debug=false'],
 )
 
 # libtool versioning