qemu security update

[15:4.2.1-15.el7]

• Document CVE-2021-4158 and CVE-2021-3947 as fixed (Mark Kanda) [Orabug: 33719302] [Orabug: 33754145] {CVE-2021-3947} {CVE-2021-4158}
• hw/block/fdc: Kludge missing floppy drive to fix CVE-2021-20196 (Philippe Mathieu-Daude) [Orabug: 32439466] {CVE-2021-20196}
• hw/block/fdc: Extract blk_create_empty_drive() (Philippe Mathieu-Daude) [Orabug: 32439466] {CVE-2021-20196}
• net: vmxnet3: validate configuration values during activate (CVE-2021-20203) (Prasad J Pandit) [Orabug: 32559476] {CVE-2021-20203}
• lan9118: switch to use qemu_receive_packet() for loopback (Alexander Bulekov) [Orabug: 32560540] {CVE-2021-3416}
• pcnet: switch to use qemu_receive_packet() for loopback (Alexander Bulekov) [Orabug: 32560540] {CVE-2021-3416}
• rtl8139: switch to use qemu_receive_packet() for loopback (Alexander Bulekov) [Orabug: 32560540] {CVE-2021-3416}
• tx_pkt: switch to use qemu_receive_packet_iov() for loopback (Jason Wang) [Orabug: 32560540] {CVE-2021-3416}
• sungem: switch to use qemu_receive_packet() for loopback (Jason Wang) [Orabug: 32560540] {CVE-2021-3416}
• dp8393x: switch to use qemu_receive_packet() for loopback packet (Jason Wang) [Orabug: 32560540] {CVE-2021-3416}
• e1000: switch to use qemu_receive_packet() for loopback (Jason Wang) [Orabug: 32560540] {CVE-2021-3416}
• net: introduce qemu_receive_packet() (Jason Wang) [Orabug: 32560540] {CVE-2021-3416}
• target/i386: Populate x86_ext_save_areas offsets using cpuid where possible (David Edmondson)
• target/i386: Observe XSAVE state area offsets (David Edmondson)
• target/i386: Make x86_ext_save_areas visible outside cpu.c (David Edmondson)
• target/i386: Pass buffer and length to XSAVE helper (David Edmondson)
• target/i386: Clarify the padding requirements of X86XSaveArea (David Edmondson)
• target/i386: Consolidate the X86XSaveArea offset checks (David Edmondson)
• target/i386: Declare constants for XSAVE offsets (David Edmondson)