Fix typos discovered by codespell (#2047)

% [`codespell --count --ignore-words-list=fo .`](https://pypi.org/project/codespell/)
```
./ninja/src/missing_deps.cc:119: dependecy ==> dependency
./ninja/src/includes_normalize-win32.cc:51: funcation ==> function
./ninja/src/eval_env.h:58: invokable ==> invocable
./ninja/src/missing_deps_test.cc:155: beacuse ==> because
./ninja/src/deps_log_test.cc:393: unparseable ==> unparsable
```

.github/workflows/linux.yml

@@ -13,6 +13,9 @@ jobs:
       image: centos:7
     steps:
     - uses: actions/checkout@v2
+    - uses: codespell-project/actions-codespell@master
+      with:
+        ignore_words_list: fo,wee
     - name: Install dependencies
       run: |
         curl -L -O https://github.com/Kitware/CMake/releases/download/v3.16.4/cmake-3.16.4-Linux-x86_64.sh

src/deps_log_test.cc

@@ -390,7 +390,7 @@ TEST_F(DepsLogTest, Truncated) {
     DepsLog log;
     EXPECT_TRUE(log.Load(kTestFilename, &state, &err));
     if (!err.empty()) {
-      // At some point the log will be so short as to be unparseable.
+      // At some point the log will be so short as to be unparsable.
       break;
     }
 

src/eval_env.h

@@ -55,7 +55,7 @@ private:
   TokenList parsed_;
 };
 
-/// An invokable build command and associated metadata (description, etc.).
+/// An invocable build command and associated metadata (description, etc.).
 struct Rule {
   explicit Rule(const std::string& name) : name_(name) {}
 

src/includes_normalize-win32.cc

@@ -48,7 +48,7 @@ bool IsPathSeparator(char c) {
 }
 
 // Return true if paths a and b are on the same windows drive.
-// Return false if this funcation cannot check
+// Return false if this function cannot check
 // whether or not on the same windows drive.
 bool SameDriveFast(StringPiece a, StringPiece b) {
   if (a.size() < 3 || b.size() < 3) {

src/missing_deps.cc

@@ -116,7 +116,7 @@ void MissingDependencyScanner::ProcessNodeDeps(Node* node, Node** dep_nodes,
     // rebuild this target when the build is reconfigured", but build.ninja is
     // often generated by a configuration tool like cmake or gn. The rest of
     // the build "implicitly" depends on the entire build being reconfigured,
-    // so a missing dep path to build.ninja is not an actual missing dependecy
+    // so a missing dep path to build.ninja is not an actual missing dependency
     // problem.
     if (deplog_node->path() == "build.ninja")
       return;

src/missing_deps_test.cc

@@ -152,7 +152,7 @@ TEST_F(MissingDependencyScannerTest, CycleInGraph) {
   CreateInitialState();
   CreateGraphDependencyBetween("compiled_object", "generated_header");
   CreateGraphDependencyBetween("generated_header", "compiled_object");
-  // The missing-deps tool doesn't deal with cycles in the graph, beacuse
+  // The missing-deps tool doesn't deal with cycles in the graph, because
   // there will be an error loading the graph before we get to the tool.
   // This test is to illustrate that.
   std::string err;