Fix for --gc-sections on NetBSD This patch fixes http://bugs.ntp.org/1844, works around http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=40401, by improving the test for support of --gc-sections to run a program which reads a file using stdio built with --gc-sections, instead of simply link the binary. This catches the buggy linker as the garbage collection removes a tag NetBSD uses to distinguish its own elf binaries from Linux ones, causing it to treat conftest as a Linux binary and run it with the wrong syscall table.