build: fix build at -O2 on rawhide
build: fix build at -O2 on rawhide

I had previously tested commit 059d746 with -O intentionally omitted
from my CFLAGS; but that means that I missed out on this warning
from gcc 4.6.2 when optimizations are enabled:

util/buf.c: In function 'virBufferGetIndent':
util/buf.c:86:1: error: function might be candidate for attribute 'pure' [-Werror=suggest-attribute=pure]

While it is probably a good idea to add the attributes and silence
this warning, it's also invasive; 'make -k' found more than 75 such
complaints.  And it doesn't help that gcc 4.6.2 is still buggy
(coreutils reported a case where gcc 4.6.2 incorrectly suggested
marking a function pure that incremented a global variable; fixed
in gcc 4.7).  So the best fix for now is to disable the warning.

It also doesn't help that I stumbled across another problem - gcc
documents that -Wsuggest-attribute=pure only warns if you use -O,
or if you use -fipa-pure-const.  But in practice, when I omitted -O
but added -fipa-pure-const, the warnings are fickle - I got warnings
for simple compilation that disappeared when I also added -fPIC.
And the way libtool compiles things is with -fPIC first, then without
-fPIC but with errors sent to /dev/null - which meant that without
disabling -Wsuggest-attribute=pure, I got a compile error with no
message.  :(  See http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10197

* m4/virt-compile-warnings.m4 (LIBVIRT_COMPILE_WARNINGS): Silence
-Wsuggest-attribute warnings for now.

dumbbell/libvirt,libvirt/libvirt,fabianfreyer/libvirt,bjzhang/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,shugaoye/libvirt,taget/libvirt,olafhering/libvirt,wiedi/libvirt,rmarwaha/libvirt1,jeckersb/libvirt,jeckersb/libvirt,rmarwaha/libvirt,novel/fbsd-libvirt,elmarco/libvirt,trainstack/libvirt,datto/libvirt,foomango/libvirt,iam-TJ/libvirt,foomango/libvirt,danwent/libvirt-ovs,novel/fbsd-libvirt,siboulet/libvirt-openvz,libvirt/libvirt,libvirt/libvirt,jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,zippy2/libvirt,agx/libvirt,crobinso/libvirt,warewolf/libvirt,dumbbell/libvirt,rmarwaha/libvirt,jfehlig/libvirt,shugaoye/libvirt,jeckersb/libvirt,zhlcindy/libvirt-1.1.4-maintain,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,wiedi/libvirt,siboulet/libvirt-openvz,datto/libvirt,danwent/libvirt-ovs,rlaager/libvirt,agx/libvirt,jeckersb/libvirt,elmarco/libvirt,jeckersb/libvirt,foomango/libvirt,elmarco/libvirt,danwent/libvirt-ovs,novel/fbsd-libvirt,crobinso/libvirt,trainstack/libvirt,crobinso/libvirt,warewolf/libvirt,rlaager/libvirt,jfehlig/libvirt,iam-TJ/libvirt,warewolf/libvirt,agx/libvirt,novel/fbsd-libvirt,novel/fbsd-libvirt,jeckersb/libvirt,eskultety/libvirt,rmarwaha/libvirt,danwent/libvirt-ovs,wiedi/libvirt,cbosdo/libvirt,trainstack/libvirt,warewolf/libvirt,shugaoye/libvirt,cbosdo/libvirt,emaste/libvirt,cbosdo/libvirt,rmarwaha/libvirt1,wiedi/libvirt,bjzhang/libvirt,VenkatDatta/libvirt,rmarwaha/libvirt,olafhering/libvirt,andreabolognani/libvirt,iam-TJ/libvirt,wiedi/libvirt,emaste/libvirt,siboulet/libvirt-openvz,rlaager/libvirt,VenkatDatta/libvirt,siboulet/libvirt-openvz,jardasgit/libvirt,taget/libvirt,novel/fbsd-libvirt,eskultety/libvirt,bjzhang/libvirt,fabianfreyer/libvirt,iam-TJ/libvirt,dumbbell/libvirt,warewolf/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,novel/fbsd-libvirt,iam-TJ/libvirt,rmarwaha/libvirt1,taget/libvirt,iam-TJ/libvirt,emaste/libvirt,rmarwaha/libvirt1,datto/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,cbosdo/libvirt,rmarwaha/libvirt,taget/libvirt,emaste/libvirt,novel/fbsd-libvirt,rlaager/libvirt,eskultety/libvirt,siboulet/libvirt-openvz,datto/libvirt,nertpinx/libvirt,taget/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,agx/libvirt,novel/fbsd-libvirt,agx/libvirt,cbosdo/libvirt,danwent/libvirt-ovs,jfehlig/libvirt,VenkatDatta/libvirt,olafhering/libvirt,bjzhang/libvirt,jfehlig/libvirt,shugaoye/libvirt,emaste/libvirt,datto/libvirt,elmarco/libvirt,nertpinx/libvirt,jardasgit/libvirt,rmarwaha/libvirt1,jeckersb/libvirt,zippy2/libvirt,dumbbell/libvirt,warewolf/libvirt,dumbbell/libvirt,foomango/libvirt,olafhering/libvirt,zippy2/libvirt,rlaager/libvirt,nertpinx/libvirt,eskultety/libvirt,rmarwaha/libvirt,nertpinx/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,trainstack/libvirt,warewolf/libvirt,zippy2/libvirt,foomango/libvirt,crobinso/libvirt,bjzhang/libvirt,trainstack/libvirt,elmarco/libvirt,trainstack/libvirt,zhlcindy/libvirt-1.1.4-maintain,rmarwaha/libvirt1,emaste/libvirt,trainstack/libvirt,fabianfreyer/libvirt,wiedi/libvirt,wiedi/libvirt,dumbbell/libvirt,iam-TJ/libvirt,libvirt/libvirt,eskultety/libvirt,emaste/libvirt