FreeBSD 11.0 lacks ELFCOMPRESS_ZLIB

FreeBSD 11.0 unfortunately lacks ELF compression definitions in their
elf.h (sys/elf_common.h), and 11.1 introduced them.
b9167d33a1

Though we can add workaround, we simply drop support because
FreeBSD 11.0 is already EOL at November 30, 2017.
https://www.freebsd.org/security/unsupported.html

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64351 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

addr2line.c

@@ -102,7 +102,8 @@ void *alloca();
 #endif
 
 #ifdef SHF_COMPRESSED
-# ifdef HAVE_LIBZ
+# if defined(ELFCOMPRESS_ZLIB) && defined(HAVE_LIBZ)
+   /* FreeBSD 11.0 lacks ELFCOMPRESS_ZLIB */
 #  include <zlib.h>
 #  define SUPPORT_COMPRESSED_DEBUG_LINE
 # endif