build: fix "missing initializer" error in qemu_process.c
    
    Found when attempting to build on Fedora 17 alpha with:
    
       ./autogen.sh --system --enable-compile-warnings=error
    
    (this same build command works without problem on Fedora 16). Since
    the consumer of the qemuProcessReconnectData doesn't assume that the
    other fields of the struct are initialized (although it uses them
    internally), the simpler solution is to just switch to C99-style
    struct initialization (which doesn't require specification of all
    fields).