lt/ltsha*.c: do not #include hash code if LT_NO_EMBED is defined

lt/ltsha*.c: do not #include hash code if LT_NO_EMBED is defined

By default, each of the ltsha*.c files can be compiled by itself
to produce a usable utility.

However, during development, it's more helpful to have each of the
source files compile to an object file and then link to the final
executable binary.

Defining LT_NO_EMBED prevents the ltsha*.c files from including the
implementation file for the specific hash each one uses.