Move #includes out of extern "C" blocks

Do some include shuffling for `**.h` files within lib, programs, tests, and zlibWrapper.
`lib/legacy` and `lib/deprecated` are untouched.
`#include`s within `extern "C"` blocks in .cpp files are untouched.

todo: shuffling for `xxhash.h`

programs/timefn.h

@@ -11,12 +11,6 @@
 #ifndef TIME_FN_H_MODULE_287987
 #define TIME_FN_H_MODULE_287987
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
-
 /*-****************************************
 *  Types
 ******************************************/
@@ -32,6 +26,11 @@ extern "C" {
   typedef unsigned long long PTime;  /* does not support compilers without long long support */
 #endif
 
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /* UTIL_time_t contains a nanosecond time counter.
  * The absolute value is not meaningful.
  * It's only valid to compute the difference between 2 measurements. */