more bogus meson warnings

[Peter Maydell]

I tried my static-system build config today; meson bogus
complaints include:

WARNING: Static library 'pulse' not found for dependency 'libpulse',
may not be statically linked
WARNING: Static library 'pulsecommon-11.1' not found for dependency
'libpulse', may not be statically linked
WARNING: Static library 'asound' not found for dependency 'alsa', may
not be statically linked
WARNING: Static library 'spice-server' not found for dependency
'spice-server', may not be statically linked
WARNING: Static library 'cacard' not found for dependency 'libcacard',
may not be statically linked

We asked for static linking, this should result in
"OK, no static library present, ignore optional feature",
not "decide we found the library and emit a warning message".

Has header "snappy-c.h" : YES
Library snappy found: YES
../../meson.build:1141: WARNING: could not link libsnappy, disabling
Has header "lzo/lzo1x.h" : YES
Library lzo2 found: YES
../../meson.build:1158: WARNING: could not link liblzo2, disabling

meson should just decide it doesn't have snappy and lzo2,
without emitting the warning.

thanks
-- PMM