Unmacroize ebrowse.c and etags.c a bit

Unmacroize ebrowse.c and etags.c a bit

* lib-src/ebrowse.c (READ_CHUNK_SIZE): Now an enum constant.
(streq, filename_eq, set_flag, has_flag): Now inline functions.
(set_flag): First arg is now an address, not an lvalue.
All callers changed.
(filename_eq, set_flag, has_flag):
Rename from FILENAME_EQ, SET_FLAG, HAS_FLAG.
All callers changed.
* lib-src/etags.c (streq, strcaseeq, strneq, strncaseeq):
Now inline functions.  Remove asserts that are unnecessary these
days (and in some cases were too-generous anyway).