Fixups for the c_std-options

Also removed an arg that is not allowed in muon and ignored by meson

meson.build

@@ -355,7 +355,7 @@ foreach it : ccs
   have_pthread = it_th.found() and it_machine.system() != 'windows'
   if it_machine.system() == 'sunos'
     # workaround for Solaris until https://github.com/mesonbuild/meson/issues/4328 is fixed
-    it_mth = declare_dependency(link_args: '-lm', native: it_native)
+    it_mth = declare_dependency(link_args: '-lm')
   else
     it_mth = it_cc.find_library('m', required: false, static: is_static_build)
   endif
@@ -631,12 +631,13 @@ if r.returncode() == 1 and get_option('subprojects_check')
   error(subproject_clean_error_msg)
 endif
 
-libzip_dep = dependency('libzip', required: get_option('use_sys_libzip'), static: is_static_build)
+libzip_dep = dependency('libzip', required: get_option('use_sys_libzip'), static: is_static_build, default_options: [ 'c_std=gnu99' ])
 if not libzip_dep.found()
   libzip_proj = subproject('libzip', default_options: [
     'default_library=static',
     'static_runtime=@0@'.format(is_static_build),
     'use_sys_openssl=@0@'.format(get_option('use_sys_libzip_openssl')),
+    'c_std=gnu99',
   ])
   libzip_dep = libzip_proj.get_variable('libzip_dep')
 endif

subprojects/rzar/meson.build

@@ -2,7 +2,7 @@ project('rzar', 'c',
   license: 'LGPL-3.0-only',
   meson_version: '>=0.55.0',
   default_options: [
-    'c_std=c99',
+    'c_std=gnu99',
   ]
 )
 

subprojects/rzwinkd/meson.build

@@ -2,7 +2,7 @@ project('rzwinkd', 'c',
   license: 'LGPL-3.0-only',
   meson_version: '>=0.55.0',
   default_options: [
-    'c_std=c99',
+    'c_std=gnu99',
   ]
 )