Set minimum Meson version to 0.48.0

This commit sets the required Meson version to >=0.48.0, and removes the
comment about building on FreeBSD requires an extra flag.

README.md

@@ -74,9 +74,6 @@ Run these commands:
     meson build
     ninja -C build
 
-If you use Meson older than 0.48.0 on FreeBSD, you need to pass an extra flag
-to prevent a linking error: `meson build -D b_lundef=false`.
-
 Install like so:
 
 	sudo ninja -C build install

meson.build

@@ -3,7 +3,7 @@ project(
 	'c',
 	version: '0.0.1',
 	license: 'MIT',
-	meson_version: '>=0.47.1',
+	meson_version: '>=0.48.0',
 	default_options: [
 		'c_std=c11',
 		'warning_level=2',