Drop support for openssl 0.9.7

097 hasn't seen a new version since 2007; we can drop support too.

This lets us remove our built-in sha256 implementation, and some
checks for old bugs.

src/common/include.am

@@ -3,7 +3,6 @@ noinst_LIBRARIES+= src/common/libor.a src/common/libor-crypto.a src/common/libor
 
 EXTRA_DIST+= \
   src/common/common_sha1.i	\
-  src/common/sha256.c		\
   src/common/Makefile.nmake
 
 #CFLAGS  = -Wall -Wpointer-arith -O2
@@ -72,4 +71,4 @@ src/common/common_sha1.i: $(libor_SOURCES) $(libor_crypto_a_SOURCES) $(COMMONHEA
 	fi
 
 src/common/util_codedigest.o: src/common/common_sha1.i
-src/common/crypto.o: src/common/sha256.c
+