+Use --with-wide-int to implement Emacs values with the type 'long long',
+even on hosts where a narrower type would do. With this option, on a
+typical 32-bit host, Emacs integers have 62 bits instead of 30.
+
+Use --enable-gcc-warnings to enable compile-time checks that warn
+about possibly-questionable C code. This is intended for developers
+and is useful with GNU-compatible compilers. On a recent GNU system
+there should be no warnings; on older and on non-GNU systems the
+generated warnings may still be useful.
+
+Use --enable-link-time-optimization to enable link-time optimizer, which
+is available in GNU compiler since version 4.5.0. If your compiler is not
+GNU or older than version 4.5.0, this option does nothing. If `configure'
+can determine number of online CPUS on your system, final link-time
+optimization and code generation is executed in parallel using one job
+per each available online CPU.
+