Make --enable-foo a requirement

Hi

--enable-foo in current qemu just means to enable foo if it founds it, otherwise just not enable it silently. This patches changed everything to use the convention:

* foo="no", feature will only be used if --enable-foo arg is given
* foo="", feature will be searched for, and if found, will be used
* foo="yes", this value vill only be set by --enable-foo flag.
feature will searched for, if not found, configure exits with error

It is important for distributions. Otherwise, if something is not installed, things don't fail to compile, just are disabled.

Once there, add --enable-foo for all things that already have --disable-foo and make sense. There are still a few bits that donot' have both --enable-foo/--disable-foo, but they are the minimal things.

kvm: the extra error message is only given if you do a --enable-kvm, by default, if kvm is not found, it just fails, as everything else.

Questions:
- sdl: anyone really uses sdl + static? I am not sure that they compile correctly, and they are just complicated.
- Do we want to sort things on the file? I.e. libraries detection toguether, features detection together, .... Just new they are a completely mess, completely unsorted as far as I can see.

Later, Juan.

Juan Quintela (20):
Make vnc configure options less verbose.
Use the same structure for list of libs in curses and pthread Add feature configure help
Add error message for feature not found
Add brlapi to new feature convencion
Add vde to new feature convencion
Add vnc_tls to new feature convencion
Add vnc_sasl to new feature convencion
Add curses to new feature convencion
Add curl to new feature convencion
Add pthread to new feature convencion
Add nptl to new feature convencion
Add bluez to new feature convencion
Add build_docs to new feature convention
Rename build_docs to docs
Add sdl to new feature convention
Add fdt to new feature convention
Add xen to new feature convention
Add kvm to new feature convention
Add sparse to new feature convention

 configure |  319 +++++++++++++++++++++++++++++++++++++++++++-----------------
 1 files changed, 228 insertions(+), 91 deletions(-)