spice: convert to meson

Faster compilation.

Removed autotools patches.

Backported meson patch to fix compilation and pkgconfig file.

Before:

time make package/spice/compile -j 12
Executed in   62.85 secs   fish           external
   usr time   56.45 secs  276.00 micros   56.45 secs
   sys time    8.06 secs   46.00 micros    8.06 secs

Before + PKG_BUILD_PARALLEL:

Executed in   45.40 secs   fish           external
   usr time   63.08 secs  253.00 micros   63.08 secs
   sys time    8.57 secs   44.00 micros    8.57 secs

After:

time make package/spice/compile -j 12
Executed in   16.54 secs   fish           external
   usr time   41.29 secs  266.00 micros   41.29 secs
   sys time    4.76 secs   45.00 micros    4.76 secs

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/spice/patches/040-only-server.patch

@@ -0,0 +1,19 @@
+--- a/meson.build
++++ b/meson.build
+@@ -192,8 +192,6 @@ add_project_arguments(compiler.get_supported_arguments(spice_server_global_cflag
+ # Subdirectories
+ #
+ subdir('server')
+-subdir('tools')
+-subdir('docs')
+ 
+ #
+ # write config.h
+--- a/server/meson.build
++++ b/server/meson.build
+@@ -186,5 +186,3 @@ spice_server_libs = both_libraries('spice-server', spice_server_sources,
+ 
+ spice_server_shared_lib = spice_server_libs.get_shared_lib()
+ spice_server_static_lib = spice_server_libs.get_static_lib()
+-
+-subdir('tests')