util: buffer: Simplify escape buffer allocations
util: buffer: Simplify escape buffer allocations

Replace combinations of xalloc_oversized and VIR_ALLOC_N_QUIET by using
g_malloc0_n which does the checking internally.

This conversion is done with a semantic difference and slightly higher
memory requirements as I've opted to allocate one chunk more than
necessary rather than trying to accomodate the NUL byte separately.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

libvirt/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,libvirt/libvirt,fabianfreyer/libvirt,zippy2/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,jfehlig/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,crobinso/libvirt,jardasgit/libvirt,fabianfreyer/libvirt