build: Increase warning level to 2

As discussed in card10/firmware!357, we should increase the number of
enabled compiler warnings to catch a lot more silent bugs.  Increase the
meson-global warning level to 2, but excluding the `unused-parameter`
and `old-style-declaration` warnings.  Additionally, disable warnings
for libraries as we cannot fix that code anyway.

Signed-off-by: Rahix <rahix@rahix.de>

lib/ff13/meson.build

@@ -16,6 +16,7 @@ lib = static_library(
   sources,
   include_directories: includes,
   dependencies: [periphdriver, mx25lba],
+  c_args: '-w',
 )
 
 libff13 = declare_dependency(

meson.build

@@ -7,6 +7,7 @@ project(
     'c_std=c99',
     'b_staticpic=false',
     'b_asneeded=false',
+    'warning_level=2',
   ],
 )
 
@@ -17,6 +18,8 @@ assert(
 )
 
 add_global_arguments(
+  '-Wno-unused-parameter',
+  '-Wno-old-style-declaration',
   meson.get_cross_property('target_defs'),
   language: 'c',
 )

pycardium/meson.build

@@ -80,6 +80,7 @@ upy = static_library(
   micropython_extmod_sources,
   mp_headers,
   include_directories: micropython_includes,
+  c_args: '-w',
 )
 
 elf = executable(