When using config.h, it must be the very first include in all source
files since it contains #define that may change the compilation process
(eg libc structure layout changes when it's used to enable large file
support on 32 bit x86 archs). This commit adds it at the beginning
of all .c and .cpp files
Every place that does a regular malloc/calloc and aborts on failure
should use spice_malloc/spice_mallo0 instead, which is leaner and cleaner.
Allocations of dynamically sized arrays can use g_malloc_n or g_new etc
which correctly handle multiplication overflow if some of the arguments
are not trusted.
