s390x: allow lifting of vector instructions

guest_s390_toIR lifts vector instructions only if host supports them,
which is never going to happen when using it on x86, so let's fool the
check.

Additionally, in context of rebasing discussion, I thought it would
make sense to make hacks like this stand out. So I wrapped it in PYVEX
ifdef.

Makefile-gcc

@@ -37,6 +37,7 @@ CFLAGS := -Ipub -Ipriv \
 	-Wcast-align -Wmissing-declarations \
 	-Wwrite-strings -Wformat -Wformat-security \
 	-std=gnu99 -fstrict-aliasing -fPIC \
+	-DPYVEX \
 	$(EXTRA_CFLAGS)
 
 # If not debugging, put -g -O2 after any flags we inherit from our invoker

Makefile-msvc

@@ -19,7 +19,7 @@ STATIC_LIBRARY_FILE = libvex.lib
 DYNAMIC_LIBRARY_FILE = libvex.dll
 EXTRA_CLEAN_FILES = auxprogs/genoffsets.exe genoffsets.obj
 
-CCFLAGS = /Ipub /Ipriv $(EXTRA_CFLAGS) /O2 /wd4715
+CCFLAGS = /Ipub /Ipriv $(EXTRA_CFLAGS) /O2 /wd4715 /DPYVEX
 
 all: vex
 

priv/main_main.c

@@ -384,6 +384,11 @@ IRSB *LibVEX_Lift (  VexTranslateArgs *vta,
    if (vta->arch_host == VexArchS390X) {
       s390_host_hwcaps = vta->archinfo_host.hwcaps;
    }
+#ifdef PYVEX
+   if (vta->arch_guest == VexArchS390X) {
+      s390_host_hwcaps |= VEX_HWCAPS_S390X_LDISP | VEX_HWCAPS_S390X_VX;
+   }
+#endif
 
    /* First off, check that the guest and host insn sets
       are supported. */