Set PL_expect less often when parsing semicolons

Set PL_expect less often when parsing semicolons

As it worked before, the parser (perly.y) would set PL_expect to
XSTATE after encountering a statement-terminating semicolon.

Two functions in op.c--package and utilize--had to set the value to
XSTATE as a result.

Also, in the case of a closing brace, the lexer emits an implicit
semicolon followed by '}' (emitted via force_next).  force_next
records the value of PL_expect and restores it when emitting the
token.  So in this case the value of PL_expect was flipping back and
forth between two values.

Instead of having the parser set it to XSTATE, we can have the lexer
set it to XSTATE by default when emitting an explicit semicolon.  (It
was setting it to XTERM.)  The parser can set it to XTERM in the only
place that matters; viz., the header of a for-loop.  This simplifies
things conceptually, and makes the code a whole line shorter.

(The diff stat shows more savings in line count, but that is because
the version of bison I used to regenerate the tables produces smaller
headers than what was already committed.)