Add fallback zero value definition for MAP_SYNC etc. even when building
for CONFIG_LINUX.

Fixes openwrt/packages#11067

Reported-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Fixes: openwrt/packages#11067

Reported-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Group configure options by the functionality category they roughly
belong to

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Supersedes openwrt/packages#8571

Reported-by: Rosen Penev rosenp@gmail.com
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

Here are the notable changes

 - pixman is now not part of the release tarball and is required as an
   external dependency
 - archipelago is removed by upstream
 - patches are regenerated with git-format-patch
 - ifunc requirement is now removed

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

At the moment, only build these softmmu emulators for x86_64 and sunxi
target.  The decision was made for the following reasons

 - It seems that interests of virtualization with qemu are mostly from
   x86, and ARM recently.
 - x86, sunxi boards/boxes capable of running qemu with accel=kvm are more
   widely available
 - Not all host, target combinations of qemu works, or even compiles
 - Extra maintenance work and server resources

Test results are as the following

 - Nested vmx works: lede-qemu-x86_64-kvm on lede-qemu-x86_64-kvm
 - KVM on Cubieboard2 works
 - tcg with malta works: lede-qemu-malta-tcg on lede-qemu-malta-tcg.
   But it's too slow to be useful thus not included in this version
 - mips64 host does not compile

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>