meson: Update minimum version to 0.57.0

Required for c++20 suppport.

Change-Id: I3d34c7ebecbb9b7a1f1f8fe43f7b36f8d1581979
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meson.build b/meson.build
index bacc792..ebf6126 100644
--- a/meson.build
+++ b/meson.build
@@ -2,7 +2,7 @@
   'sdeventplus',
   'cpp',
   version: '0.1',
-  meson_version: '>=0.53.2',
+  meson_version: '>=0.57.0',
   default_options: [
     'warning_level=3',
     'cpp_std=c++17',
diff --git a/src/meson.build b/src/meson.build
index 288186b..29877dd 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -7,11 +7,11 @@
   dependencies: function2_dep,
   required: false)
 if not has_function2
+  function2_opts = import('cmake').subproject_options()
+  function2_opts.add_cmake_defines({'BUILD_TESTING': 'OFF'})
   function2_proj = import('cmake').subproject(
     'function2',
-    cmake_options: [
-      '-DBUILD_TESTING=OFF',
-    ],
+    options: function2_opts,
     required: false)
   assert(function2_proj.found(), 'function2 is required')
   if function2_proj.found()
diff --git a/test/meson.build b/test/meson.build
index 97e219b..29704ca 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -1,11 +1,11 @@
 gtest = dependency('gtest', main: true, disabler: true, required: false)
 gmock = dependency('gmock', disabler: true, required: false)
 if not gtest.found() or not gmock.found()
+  gtest_opts = import('cmake').subproject_options()
+  gtest_opts.add_cmake_defines({'CMAKE_CXX_FLAGS': '-Wno-pedantic'})
   gtest_proj = import('cmake').subproject(
     'googletest',
-    cmake_options: [
-      '-DCMAKE_CXX_FLAGS=-Wno-pedantic',
-    ],
+    options: gtest_opts,
     required: false)
   if gtest_proj.found()
     gtest = declare_dependency(