fix build problem with glibc 2.24
x86: Disallow L3 recursive pagetable for 32-bit PV guests [XSA-185,
CVE-2016-7092]
x86: Mishandling of instruction pointer truncation during emulation
[XSA-186, CVE-2016-7093]
x86 HVM: Overflow of sh_ctxt->seg_reg[] [XSA-187, CVE-2016-7094]