Fix typos in clang

Found via codespell -q 3 -I ../clang-whitelist.txt
Where whitelist consists of:

  archtype
  cas
  classs
  checkk
  compres
  definit
  frome
  iff
  inteval
  ith
  lod
  methode
  nd
  optin
  ot
  pres
  statics
  te
  thru

Patch by luzpaz! (This is a subset of D44188 that applies cleanly with a few
files that have dubious fixes reverted.)

Differential revision: https://reviews.llvm.org/D44188

llvm-svn: 329399
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 6468d1a..cc43b6a 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -4988,7 +4988,7 @@
    * for "int x", indicating that the current argument will initialize that
    * parameter. After typing further, to \c add(17, (where the code-completion
    * point is after the ","), the code-completion string will contain a
-   * "current paremeter" chunk to "int y".
+   * "current parameter" chunk to "int y".
    */
   CXCompletionChunk_CurrentParameter,
   /**
@@ -5409,7 +5409,7 @@
  * user types punctuation characters or whitespace, at which point the
  * code-completion location will coincide with the cursor. For example, if \c p
  * is a pointer, code-completion might be triggered after the "-" and then
- * after the ">" in \c p->. When the code-completion location is afer the ">",
+ * after the ">" in \c p->. When the code-completion location is after the ">",
  * the completion results will provide, e.g., the members of the struct that
  * "p" points to. The client is responsible for placing the cursor at the
  * beginning of the token currently being typed, then filtering the results