[meson] Remove with_libstdcxx build option

This was done in #770 but no indication of anyone is using it,
let's remove it from our meson port and we can just don't care about
it in autotools port after the migration to meson.
diff --git a/meson_options.txt b/meson_options.txt
index a6dea29..e68a83f 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -30,7 +30,5 @@
 
 option('icu_builtin', type: 'boolean', value: false,
   description: 'Don\'t separate ICU support as harfbuzz-icu module')
-option('with_libstdcxx', type: 'boolean', value: false,
-  description: 'Allow linking with libstdc++')
 option('experimental_api', type: 'boolean', value: false,
   description: 'Enable experimental APIs')
diff --git a/src/meson.build b/src/meson.build
index c85103d..1238e0b 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -365,13 +365,6 @@
   harfbuzz_deps += [icu_dep]
 endif
 
-if get_option('with_libstdcxx')
-  chosen_linker = 'cpp'
-else
-  # Use a C linker, not C++; Don't link to libstdc++
-  chosen_linker = 'c'
-endif
-
 # harfbuzz
 gen_def = find_program('gen-def.py')
 
@@ -405,7 +398,7 @@
   soversion: hb_so_version,
   version: version,
   install: true,
-  link_language: chosen_linker,
+  link_language: 'c',
 )
 
 libharfbuzz_dep = declare_dependency(
@@ -428,7 +421,7 @@
   soversion: hb_so_version,
   version: version,
   install: true,
-  link_language: chosen_linker,
+  link_language: 'c',
 )
 
 libharfbuzz_subset_dep = declare_dependency(
@@ -528,7 +521,7 @@
     version: version,
     install: true,
     # ICU links to stdc++ anyway so the default linker is good
-    # link_language: chosen_linker,
+    # link_language: 'c',
   )
 
   libharfbuzz_icu_dep = declare_dependency(
@@ -612,7 +605,7 @@
     soversion: hb_so_version,
     version: version,
     install: true,
-    link_language: chosen_linker,
+    link_language: 'c',
   )
 
   gir = find_program('g-ir-scanner', required: get_option('introspection'))
@@ -680,11 +673,7 @@
   env.set('HBHEADERS', ' '.join(hb_headers))
 
   if cpp.get_id() != 'msvc' and not meson.is_cross_build() # ensure the local tools are usable
-    # See https://github.com/mesonbuild/meson/pull/6838
-    if meson.version().version_compare('>=0.54.999') and not get_option('with_libstdcxx')
-      dist_check_script += 'check-libstdc++'
-    endif
-    dist_check_script += ['check-static-inits', 'check-symbols']
+    dist_check_script += ['check-libstdc++', 'check-static-inits', 'check-symbols']
   endif
 
   foreach name : dist_check_script