Use array_lengthof; NFC.

llvm-svn: 219935
diff --git a/clang/tools/driver/driver.cpp b/clang/tools/driver/driver.cpp
index db356b7..3e98b2c 100644
--- a/clang/tools/driver/driver.cpp
+++ b/clang/tools/driver/driver.cpp
@@ -246,7 +246,7 @@
     bool FoundMatch = false;
     size_t i;
 
-    for (i = 0; i < sizeof(suffixes) / sizeof(suffixes[0]); ++i) {
+    for (i = 0; i < llvm::array_lengthof(suffixes); ++i) {
       if (ProgNameRef.endswith(suffixes[i].Suffix)) {
         FoundMatch = true;
         SmallVectorImpl<const char *>::iterator it = ArgVector.begin();