wasm64: Enable to propagate -sMEMORY64 flag to Emscripten

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

Author: ktock

configure

@@ -182,6 +182,8 @@ EXTRA_CXXFLAGS=""
 EXTRA_OBJCFLAGS=""
 EXTRA_LDFLAGS=""
 
+wasm64_memory64=1
+
 # Default value for a variable defining feature "foo".
 #  * foo="no"  feature will only be used if --enable-foo arg is given
 #  * foo=""    feature will be searched for, and if found, will be used
@@ -239,6 +241,8 @@ for opt do
   ;;
   --without-default-features) default_feature="no"
   ;;
+  --wasm64-memory64=*) wasm64_memory64="$optarg"
+  ;;
   esac
 done
 
@@ -537,7 +541,7 @@ case "$cpu" in
     CPU_CFLAGS="-m32"
     ;;
   wasm64)
-    CPU_CFLAGS="-m64 -sMEMORY64=1"
+    CPU_CFLAGS="-m64 -sMEMORY64=$wasm64_memory64"
     ;;
 esac
 
@@ -795,6 +799,8 @@ for opt do
   ;;
   --disable-rust) rust=disabled
   ;;
+  --wasm64-memory64=*)
+  ;;
   # everything else has the same name in configure and meson
   --*) meson_option_parse "$opt" "$optarg"
   ;;
@@ -920,6 +926,8 @@ Advanced options (experts only):
   --disable-containers     don't use containers for cross-building
   --container-engine=TYPE  which container engine to use [$container_engine]
   --gdb=GDB-path           gdb to use for gdbstub tests [$gdb_bin]
+  --wasm64-memory64        Used only for wasm64 build. Set -sMEMORY64 of
+                           Emscripten to 1(default) or 2 (choices: 1/2)
 EOF
   meson_options_help
 cat << EOF