bug#18253: 24.4.50; doc string of `remq': correct it per the doc of `remove'

[Drew Adams]

Please explicitly say that `remq' returns a *copy* of LIST, just as we
do in the doc string of `remove'.  It does *not* "Return LIST with all
occurrences of ELT removed."  

The final sentence of the doc string tries to clarify things, but
combined with the first sentence the result is still confusing.



In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-06-28 on ODIEONE
Bzr revision: 117431 rgm@gnu.org-20140628015517-eku6hj8mpgcvfnso
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''