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.

include/complex.h

@@ -101,6 +101,7 @@ double creal(double complex);
 float crealf(float complex);
 long double creall(long double complex);
 
+#ifndef __cplusplus
 #define __CIMAG(x, t) \
 	((union { _Complex t __z; t __xy[2]; }){(_Complex t)(x)}.__xy[1])
 
@@ -111,6 +112,7 @@ long double creall(long double complex);
 #define cimag(x) __CIMAG(x, double)
 #define cimagf(x) __CIMAG(x, float)
 #define cimagl(x) __CIMAG(x, long double)
+#endif
 
 #define __CMPLX(x, y, t) \
 	((union { _Complex t __z; t __xy[2]; }){.__xy = {(x),(y)}}.__z)

include/pthread.h

@@ -84,7 +84,9 @@ __attribute__((const))
 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 *);

include/threads.h

@@ -51,7 +51,9 @@ void thrd_yield(void);
 
 thrd_t thrd_current(void);
 int thrd_equal(thrd_t, thrd_t);
+#ifndef __cplusplus
 #define thrd_equal(A, B) ((A) == (B))
+#endif
 
 void call_once(once_flag *, void (*)(void));