reported upstream to rt@openssl.org on 24 Apr 2009:
http://rt.openssl.org/Ticket/Display.html?id=1908

--- Configure
+++ Configure
@@ -499,6 +499,9 @@
 "debug-VC-WIN32","cl:-W3 -WX -Gs0 -GF -Gy -Zi -nologo -DOPENSSL_SYSNAME_WIN32 -DWIN32_LEAN_AND_MEAN -DL_ENDIAN -D_CRT_SECURE_NO_DEPRECATE:::WIN32::BN_LLONG RC4_INDEX EXPORT_VAR_AS_FN ${x86_gcc_opts}:${x86_asm}:win32n:win32",
 "VC-CE","cl::::WINCE::BN_LLONG RC4_INDEX EXPORT_VAR_AS_FN ${x86_gcc_opts}:${no_asm}:win32",
 
+# Interix (GCC)
+"interix-gcc", "gcc:-D_ALL_SOURCE -DL_ENDIAN -DTERMIOS -O2 -Wall::-D_REENTRANT::-ldl::${no_asm}:dlfcn:gnu:::.so.\$(SHLIB_MAJOR).\$(SHLIB_MINOR)",
+
 # Borland C++ 4.5
 "BC-32","bcc32::::WIN32::BN_LLONG DES_PTR RC4_INDEX EXPORT_VAR_AS_FN:${no_asm}:win32",
 
--- config
+++ config
@@ -344,6 +344,10 @@
 	echo "mips-sony-newsos4"; exit 0;
 	;;
 
+	Interix*)
+	echo "i586-pc-interix${VERSION}"; exit 0;
+	;;
+
     MINGW*)
 	echo "${MACHINE}-whatever-mingw"; exit 0;
 	;;
@@ -807,6 +811,7 @@
   t3e-cray-unicosmk) OUT="cray-t3e" ;;
   j90-cray-unicos) OUT="cray-j90" ;;
   nsr-tandem-nsk) OUT="tandem-c89" ;;
+  *-interix*) OUT="interix-gcc" ;;
   beos-*) OUT="$GUESSOS" ;;
   x86pc-*-qnx6) OUT="QNX6-i386" ;;
   *-*-qnx6) OUT="QNX6" ;;