Use SSL_CPPFLAGS only for compiling crypt.c

Use SSL_CPPFLAGS only for compiling crypt.c

The previous cleanups moved everything which depends on openssl to
crypt.c. This is now the only file which includes openssl headers,
so there is no need to compile all objects with the ssl cpp flags.
In fact this could break things for setups on which the include dir
for openss contains other unwanted header files.