Remove checked-in binary for test/lld/em_asm_pthread.cpp. NFC (#8392)

This was was added back in #3714, but with a checked in binaryen instead
of a .wat file

This change fixes `generate_lld_tests.py` so that it can build
`em_asm_pthread.cpp` correctly and converts the test from a wasm to a
wat test.

The important part of the test I beleive is the `(start
$__wasm_init_memory)` which exists in the new `.wat` file.

Author: sbc100

scripts/test/generate_lld_tests.py

@@ -69,6 +69,10 @@ def generate_wat_files(llvm_bin, emscripten_sysroot):
         # were included.
         if 'longjmp' in src_file:
             link_cmd.append('--strip-debug')
+        if 'pthread' in src_file:
+            compile_cmd.append('-pthread')
+            link_cmd.append('--import-memory')
+            link_cmd.append('--shared-memory')
         if is_shared:
             compile_cmd.append('-fPIC')
             compile_cmd.append('-fvisibility=default')

test/lld/em_asm_pthread.cpp

@@ -1,6 +1,6 @@
 // Build with
 //
-// emcc a.cpp -pthread -s WASM_BIGINT
+// emcc a.cpp -pthread
 //
 
 #include <emscripten.h>