unified build scheme: add build.info files

Now that we have the foundation for the "unified" build scheme in
place, we add build.info files.  They have been generated from the
Makefiles in the same directories.  Things that are platform specific
will appear in later commits.

Reviewed-by: Andy Polyakov <appro@openssl.org>

crypto/md5/build.info

@@ -0,0 +1,3 @@
+LIBS=../../libcrypto
+SOURCE[../../libcrypto]=\
+        md5_dgst.c md5_one.c {- $target{md5_asm_src} -}