package/qemu: pixman only used for system emulation

When we initially introduced the target qemu in 98e1a6b9619c
(package/qemu: build for the target (i386 or x86_64 only)), we
unconditionally enabled all the system and user emulation without
distinction, so pixman was made a mandatory dependency.

However, soon afterwards, in 68ec49acc7be (package/qemu: add basic
target selection), we added an option to enable/disable the system
emulation, but the dependency on pixman was not moved to that new
option.

Fix that now, and only depend on pixman when system emulation is
enabled.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2 files changed