build: add configure check for having memfd_create() API

config.h.meson

@@ -19,6 +19,10 @@
 /* Gettext package */
 #mesondefine GETTEXT_PACKAGE
 
+/* Define to 1 if you have the declaration of `memfd_create', and to 0 if you
+   don't. */
+#mesondefine HAVE_DECL_MEMFD_CREATE
+
 /* Define to 1 if you have the declaration of `reallocarray', and to 0 if
    you don't. */
 #mesondefine HAVE_DECL_REALLOCARRAY

configure.ac

@@ -81,6 +81,12 @@ AC_CHECK_DECLS([
 #include <malloc.h>
 ]])
 
+AC_CHECK_DECLS([
+	memfd_create],
+	[], [], [[
+#include <sys/mman.h>
+]])
+
 AC_CHECK_HEADERS(sys/auxv.h)
 
 AC_CHECK_DECLS([getrandom],

meson.build

@@ -115,6 +115,7 @@ config_h.set('HAVE_SECURE_GETENV', cc.has_function('secure_getenv'))
 config_h.set('HAVE___SECURE_GETENV', cc.has_function('__secure_getenv'))
 config_h.set10('HAVE_DECL_REALLOCARRAY', cc.has_function('reallocarray', prefix: '#include <malloc.h>'))
 config_h.set10('HAVE_DECL_EXPLICIT_BZERO', cc.has_function('explicit_bzero', prefix: '#include <string.h>'))
+config_h.set10('HAVE_DECL_MEMFD_CREATE', cc.has_function('memfd_create', prefix: '#include <sys/mman.h>'))
 
 # types
 config_h.set('SIZEOF_DEV_T', cc.sizeof('dev_t', prefix: '#include <sys/types.h>'))