Add memfd-create option

Add a meson build option, memfd-create, that controls whether the
memfd_create system call support will be enabled.  The default value
is true so that it will be enabled, but it allows users like AGL
that currently has issues with security labels and memfd to disable
it.

Upstream-Status: Pending

Signed-off-by: Scott Murray <scott.murray@konsulko.com>

diff --git a/meson.build b/meson.build
index 82107e1..9d042ca 100644
--- a/meson.build
+++ b/meson.build
@@ -78,8 +78,12 @@ elif cc.has_header_symbol('sys/mkdev.h', 'major')
 endif
 
 optional_libc_funcs = [
-	'mkostemp', 'strchrnul', 'initgroups', 'posix_fallocate', 'memfd_create'
+	'mkostemp', 'strchrnul', 'initgroups', 'posix_fallocate'
 ]
+if get_option('memfd-create')
+	optional_libc_funcs += [ 'memfd_create' ]
+endif
+
 foreach func : optional_libc_funcs
 	if cc.has_function(func)
 		config_h.set('HAVE_' + func.to_upper(), 1)
diff --git a/meson_options.txt b/meson_options.txt
index 80a2ad7..4a93472 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -99,6 +99,13 @@ option(
 	description: 'systemd service plugin: state notify, watchdog, socket activation'
 )
 
+option(
+	'memfd-create',
+	type: 'boolean',
+	value: true,
+	description: 'Use memfd_create system call'
+)
+
 option(
 	'remoting',
 	type: 'boolean',