Rename upstream directory to simply prebuilt

The name `upstream` doesn't have any meaning anymore now that there is
no more fastcomp.  It was removed from the SDK names in #1166 and this
is the last usage of that name/term.

.gitignore

@@ -15,9 +15,7 @@ __pycache__
 # File that get download/extracted by emsdk itself
 /ccache
 /gnu
-/upstream
-/fastcomp
-/fastcomp-clang/
+/prebuilt
 /llvm
 /ninja
 /releases

emsdk.py

@@ -1919,9 +1919,9 @@ def install_sdk(self):
       return False
 
     if getattr(self, 'custom_install_script', None) == 'emscripten_npm_install':
-      # upstream tools have hardcoded paths that are not stored in emsdk_manifest.json registry
-      install_path = 'upstream'
-      emscripten_dir = os.path.join(EMSDK_PATH, install_path, 'emscripten')
+      # prebuilt sdk tools have hardcoded paths that are not stored in
+      # emsdk_manifest.json registry
+      emscripten_dir = os.path.join(EMSDK_PATH, 'prebuilt', 'emscripten')
       # Older versions of the sdk did not include the node_modules directory
       # and require `npm ci` to be run post-install
       if not os.path.exists(os.path.join(emscripten_dir, 'node_modules')):
@@ -2244,7 +2244,7 @@ def load_releases_info():
 
 
 def get_installed_sdk_version():
-  version_file = sdk_path(os.path.join('upstream', '.emsdk_version'))
+  version_file = sdk_path(os.path.join('prebuilt', '.emsdk_version'))
   if not os.path.exists(version_file):
     return None
   with open(version_file) as f:

emsdk_manifest.json

@@ -38,7 +38,7 @@
     "macos_url": "https://storage.googleapis.com/webassembly/emscripten-releases-builds/mac/%releases-tag%/wasm-binaries.tbz2",
     "windows_url": "https://storage.googleapis.com/webassembly/emscripten-releases-builds/win/%releases-tag%/wasm-binaries.zip",
     "zipfile_prefix": "%releases-tag%-",
-    "install_path": "upstream",
+    "install_path": "prebuilt",
     "activated_path": "%installation_dir%/emscripten",
     "activated_cfg": "LLVM_ROOT='%installation_dir%/bin';BINARYEN_ROOT='%installation_dir%';EMSCRIPTEN_ROOT='%installation_dir%/emscripten'",
     "emscripten_releases_hash": "%releases-tag%"
@@ -51,7 +51,7 @@
     "macos_url": "https://storage.googleapis.com/webassembly/emscripten-releases-builds/mac/%releases-tag%/wasm-binaries-arm64.tbz2",
     "linux_url": "https://storage.googleapis.com/webassembly/emscripten-releases-builds/linux/%releases-tag%/wasm-binaries-arm64.tbz2",
     "zipfile_prefix": "%releases-tag%-",
-    "install_path": "upstream",
+    "install_path": "prebuilt",
     "activated_path": "%installation_dir%/emscripten",
     "activated_cfg": "LLVM_ROOT='%installation_dir%/bin';BINARYEN_ROOT='%installation_dir%';EMSCRIPTEN_ROOT='%installation_dir%/emscripten'",
     "emscripten_releases_hash": "%releases-tag%"