lib/Makefile.in has wrong handling of multi-word CC flags

[Sven Mueller]

Hi.

As found recently due to an attempt of Uwe Hermann at compiling all of
Debian with Open64, at least lib/Makefile.in doesn't handle multi-word
$(CC) well. When it calls config2header, it should be:

$(srcdir)/../tools/config2header CC="$(CC)" $(srcdir)/imapopts.c \
$(srcdir)/imapopts.h < $(srcdir)/imapoptions

and not

$(srcdir)/../tools/config2header CC=$(CC) $(srcdir)/imapopts.c \
$(srcdir)/imapopts.h < $(srcdir)/imapoptions

As far as I could tell for now, this is the only location of the given
problem. Other locations also have $(CC) somewhere in the parameters
given to programs, but all of those seem to just pass anything after the
first non-option parameter to that program. It exists both in 2.3.8 as
well as in 2.2.13.

Ciao,
Sven