Add PaX work-around

configure

@@ -826,6 +826,7 @@ enable_libtool_lock
 enable_portable_binary
 with_gcc_arch
 enable_maintainer_mode
+enable_pax_emutramp
 enable_debug
 enable_structs
 enable_raw_api
@@ -1473,6 +1474,7 @@ Optional Features:
                           unportable binaries
   --enable-maintainer-mode  enable make rules and dependencies not useful
 			  (and sometimes confusing) to the casual installer
+  --enable-pax_emutramp       enable pax emulated trampolines, for we can't use PROT_EXEC
   --enable-debug          debugging mode
   --disable-structs       omit code for struct support
   --disable-raw-api       make the raw api unavailable
@@ -14457,6 +14459,16 @@ $as_echo "#define SYMBOL_UNDERSCORE 1" >>confdefs.h
     fi
 fi
 
+# On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC.
+# Check whether --enable-pax_emutramp was given.
+if test "${enable_pax_emutramp+set}" = set; then :
+  enableval=$enable_pax_emutramp; if test "$enable_pax_emutramp" = "yes"; then
+
+$as_echo "#define FFI_MMAP_EXEC_EMUTRAMP_PAX 1" >>confdefs.h
+
+  fi
+fi
+
 
 FFI_EXEC_TRAMPOLINE_TABLE=0
 case "$target" in