Support Emscripten EH/SjLj in Wasm64 (#14357)

This mostly changes some `uint32_t`s to `uintptr_t` in libraries for EH
and SjLj to support wasm64.

More details in case you are interested:
1. I described in https://reviews.llvm.org/D101985 how changing the
   first argument of `emscripten_longjmp` in turn changed `testSetjmp`'s
   first argument to `uintptr_t`.
2. `testSetjmp`'s first argument `id` is compared with the local
   variable `curr`. So it's `uintptr_t` now:
   [Link](https://github.com/emscripten-core/emscripten/blob/aa2bad5d6a0de5b175688fc8ead46f70a1b43a0d/system/lib/compiler-rt/emscripten_setjmp.c#L53)
3. That `curr` is set from `table[i].id`, which is `TableEntry.id`. So
   `id` in `TableEntry` here is now `uintptr_t`:
   [Link](https://github.com/emscripten-core/emscripten/blob/aa2bad5d6a0de5b175688fc8ead46f70a1b43a0d/system/lib/compiler-rt/emscripten_setjmp.c#L51)
4. Because `table[i].id` is set from `setjmpId`, `setjmpId` needs to be
   `uintptr_t` too:
   [Link](https://github.com/emscripten-core/emscripten/blob/aa2bad5d6a0de5b175688fc8ead46f70a1b43a0d/system/lib/compiler-rt/emscripten_setjmp.c#L31)
5. Because `setjmpId` is stored in `env` (first parameter) in
   `saveSetjmp`, `saveSetjmp`'s first argument has to change to
   `uintptr_t`:
   [Link](https://github.com/emscripten-core/emscripten/blob/aa2bad5d6a0de5b175688fc8ead46f70a1b43a0d/system/lib/compiler-rt/emscripten_setjmp.c#L28)

Not sure how to add tests for this given that wasm64 support is not
ready yet. Existing tests run fine.

Author: aheejin

system/lib/compiler-rt/emscripten_exception_builtins.c

@@ -9,12 +9,13 @@
  * See: https://llvm.org/doxygen/WebAssemblyLowerEmscriptenEHSjLj_8cpp.html
  */
 
+#include <stdint.h>
 #include <threads.h>
 
-thread_local int __THREW__ = 0;
+thread_local uintptr_t __THREW__ = 0;
 thread_local int __threwValue = 0;
 
-void setThrew(int threw, int value) {
+void setThrew(uintptr_t threw, int value) {
   if (__THREW__ == 0) {
     __THREW__ = threw;
     __threwValue = value;

system/lib/compiler-rt/emscripten_setjmp.c

@@ -9,17 +9,21 @@
 #include <stdlib.h>
 #include <setjmp.h>
 
-static uint32_t setjmpId = 0;
+// 0 - Nothing thrown
+// 1 - Exception thrown
+// Other values - jmpbuf pointer in the case that longjmp was thrown
+static uintptr_t setjmpId = 0;
 
 typedef struct TableEntry {
-  uint32_t id, label;
+  uintptr_t id;
+  uint32_t label;
 } TableEntry;
 
 extern void setTempRet0(uint32_t value);
 extern void setThrew(uintptr_t threw, int value);
 extern void _emscripten_throw_longjmp(); // defined in src/library.js
 
-TableEntry* saveSetjmp(uint32_t* env, uint32_t label, TableEntry* table, uint32_t size) {
+TableEntry* saveSetjmp(uintptr_t* env, uint32_t label, TableEntry* table, uint32_t size) {
   // Not particularly fast: slow table lookup of setjmpId to label. But setjmp
   // prevents relooping anyhow, so slowness is to be expected. And typical case
   // is 1 setjmp per invocation, or less.
@@ -45,10 +49,10 @@ TableEntry* saveSetjmp(uint32_t* env, uint32_t label, TableEntry* table, uint32_
   return table;
 }
 
-uint32_t testSetjmp(uint32_t id, TableEntry* table, uint32_t size) {
-  uint32_t i = 0, curr;
+uint32_t testSetjmp(uintptr_t id, TableEntry* table, uint32_t size) {
+  uint32_t i = 0;
   while (i < size) {
-    uint32_t curr = table[i].id;
+    uintptr_t curr = table[i].id;
     if (curr == 0) break;
     if (curr == id) {
       return table[i].label;