libxl: use Linux-compatible names for sse4 cpuid features

Linux uses sse4_1 and sse4_2, but at the moment libxl uses '.' instead
of '_'.  This makes it confusing for people looking in Linux's /proc/cpuinfo
to disable features.

Add the Linux feature names, keeping the old ones for compatability.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Ian Campbell <ian.camppbell@citrix.com>

docs/man/xl.cfg.pod.5

@@ -808,7 +808,7 @@ cmplegacy cmpxchg16 cmpxchg8 cntxid dca de ds dscpl dtes64 est extapic f16c
 ffxsr fma4 fpu fxsr htt hypervisor ia64 ibs lahfsahf lm lwp mca mce misalignsse
 mmx mmxext monitor movbe msr mtrr nodeid nx osvw osxsave pae page1gb pat pbe
 pclmulqdq pdcm pge popcnt pse pse36 psn rdtscp skinit smx ss sse sse2 sse3
-sse4.1 sse4.2 sse4a ssse3 svm svm_decode svm_lbrv svm_npt svm_nrips
+sse4_1 sse4_2 sse4a ssse3 svm svm_decode svm_lbrv svm_npt svm_nrips
 svm_pausefilt svm_tscrate svm_vmcbclean syscall sysenter tbm tm tm2 topoext tsc
 vme vmx wdt x2apic xop xsave xtpr
 

tools/libxl/libxl_cpuid.c

@@ -99,8 +99,11 @@ int libxl_cpuid_parse_config(libxl_cpuid_policy_list *cpuid, const char* str)
         {"popcnt",       0x00000001, NA, CPUID_REG_ECX, 23,  1},
         {"movbe",        0x00000001, NA, CPUID_REG_ECX, 22,  1},
         {"x2apic",       0x00000001, NA, CPUID_REG_ECX, 21,  1},
+        /* Linux uses sse4_{1,2}.  Keep sse4.{1,2} for compatibility */
         {"sse4.2",       0x00000001, NA, CPUID_REG_ECX, 20,  1},
+        {"sse4_2",       0x00000001, NA, CPUID_REG_ECX, 20,  1},
         {"sse4.1",       0x00000001, NA, CPUID_REG_ECX, 19,  1},
+        {"sse4_1",       0x00000001, NA, CPUID_REG_ECX, 19,  1},
         {"dca",          0x00000001, NA, CPUID_REG_ECX, 18,  1},
         {"pdcm",         0x00000001, NA, CPUID_REG_ECX, 15,  1},
         {"xtpr",         0x00000001, NA, CPUID_REG_ECX, 14,  1},