compile_et.c: Change the emitted name of the struct error_table

compile_et.c: Change the emitted name of the struct error_table
	to be et_XXX_error_table, instead of it being a static
	variable named "et".  (This change has already been made
	in the awk versions of compile_et.)

com_err.h, com_err.c: Remove the void *priv argument from
	com_err_va() and et_com_err() experimental API's.  (That
	was a braino; the private data pointer should come from
	the hook_func_data field.)

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@9821 dc483132-0cff-0310-8789-dd5450dbe970