don't shadow functions with macros in C++

C++ programmers typically expect something like "::function(x,y)" to work
and may be surprised to find that "(::function)(x,y)" is actually required
due to the headers declaring a macro version of some standard functions.

We already omit function-like macros for C++ in most cases where there is
a real function available. This commit extends this to the remaining
function-like macros which have a real function version.
diff --git a/include/pthread.h b/include/pthread.h
index f7c9568..2697e8b 100644
--- a/include/pthread.h
+++ b/include/pthread.h
@@ -84,7 +84,9 @@
 pthread_t pthread_self(void);
 
 int pthread_equal(pthread_t, pthread_t);
+#ifndef __cplusplus
 #define pthread_equal(x,y) ((x)==(y))
+#endif
 
 int pthread_setcancelstate(int, int *);
 int pthread_setcanceltype(int, int *);