Update brace style.

Add braces around single-line blocks, and remove line breaks before
function-opening braces.

This resolves #537.

msvc/projects/vc2015/test_threads/test_threads.cpp

@@ -16,8 +16,7 @@ using std::thread;
 using std::uniform_int_distribution;
 using std::minstd_rand;
 
-int test_threads()
-{
+int test_threads() {
   je_malloc_conf = "narenas:3";
   int narenas = 0;
   size_t sz = sizeof(narenas);