syntax-check: fix violations and implement sc_prohibit_space_semicolon.

syntax-check: fix violations and implement sc_prohibit_space_semicolon.

No need for a spurious space before a command ending semi-colon.
* cfg.mk (sc_prohibit_space_semicolon): New test to catch
accidental reintroduction of spurious spaces removed by this
changeset.
* bootstrap, build-aux/general.m4sh, build-aux/ltmain.m4sh,
libltdl/lt__strl.c, m4/libtool.m4, m4/ltdl.m4, tests/bindir.at:
Remove spurious spaces.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>