Should match b_lundef in meson(1).

Index: meson.build
--- meson.build.orig
+++ meson.build
@@ -155,7 +155,6 @@ endif
 # cast checks, asserts, and additional link options.
 release_link_args = []
 test_link_args = [
-  '-Wl,-z,defs',   # Detect and reject underlinking
   '-Wl,-z,now',    # Disable lazy binding
   '-Wl,-z,relro',  # Read-only segments after relocation
 ]