fix typo in libiberty check

meson.build

@@ -566,7 +566,7 @@ endif
 # location of libiberty.h
 #
 if compiler.find_library('iberty',
-                         required:false)
+                         required:false).found()
     if compiler.has_header('libiberty.h',
                            args: cflags,
                            include_directories: include_directories(incdirs))