I managed to complete the patch fixing this problem.
I can successfully compile openssl with solaris-x86-cc (ABI=32 in mk.conf)
and with solaris64-x86_64-cc (ABI=64 in mk.conf)
Here is the patch:

--- Makefile.orig       2006-01-24 14:31:33.000000000 +0100
+++ Makefile    2006-01-24 15:00:02.000000000 +0100
@@ -48,12 +48,28 @@
 CONFIGURE_ARGS+=       --openssldir=${PKG_SYSCONFDIR:Q}
 CONFIGURE_ARGS+=       shared

-.if ${OPSYS} == "SunOS" && ${MACHINE_ARCH} == "sparc"
+.if ${OPSYS} == "SunOS"
 CONFIGURE_SCRIPT=      ./Configure
-.  if !empty(CC_VERSION:Mgcc*)
+.  if ${MACHINE_ARCH} == "sparc"
+.    if !empty(CC_VERSION:Mgcc*)
 CONFIGURE_ARGS+=       solaris-${SPARC_TARGET_ARCH}-gcc
-.  else
+.    else
 CONFIGURE_ARGS+=       solaris-${SPARC_TARGET_ARCH}-cc
+.    endif
+.  elif ${MACHINE_ARCH} == "i386"
+.    if defined(ABI) && ${ABI} == "64"
+.      if !empty(CC_VERSION:Mgcc*)
+CONFIGURE_ARGS+=       solaris64-x86_64-gcc
+.      else
+CONFIGURE_ARGS+=       solaris64-x86_64-cc
+.      endif
+.    else
+.      if !empty(CC_VERSION:Mgcc*)
+CONFIGURE_ARGS+=       solaris-x86-gcc
+.      else
+CONFIGURE_ARGS+=       solaris-x86-cc
+.      endif
+.    endif
 .  endif
 .elif ${OPSYS} == "IRIX"
 CONFIGURE_ARGS+=       no-asm


-- 
Krzysztof Raczkowski
raczkow@prz.edu.pl