add creal/cimag macros in complex.h (and use them in the functions defs)

src/complex/cimag.c

@@ -2,6 +2,5 @@
 
 double (cimag)(double complex z)
 {
-	union dcomplex u = {z};
-	return u.a[1];
+	return cimag(z);
 }

src/complex/cimagf.c

@@ -2,6 +2,5 @@
 
 float (cimagf)(float complex z)
 {
-	union fcomplex u = {z};
-	return u.a[1];
+	return cimagf(z);
 }

src/complex/cimagl.c

@@ -2,6 +2,5 @@
 
 long double (cimagl)(long double complex z)
 {
-	union lcomplex u = {z};
-	return u.a[1];
+	return cimagl(z);
 }

src/complex/creal.c

@@ -1,6 +1,6 @@
 #include <complex.h>
 
-double creal(double complex z)
+double (creal)(double complex z)
 {
-	return z;
+	return creal(z);
 }

src/complex/crealf.c

@@ -1,6 +1,6 @@
 #include <complex.h>
 
-float crealf(float complex z)
+float (crealf)(float complex z)
 {
-	return z;
+	return crealf(z);
 }

src/complex/creall.c

@@ -1,6 +1,6 @@
 #include <complex.h>
 
-long double creall(long double complex z)
+long double (creall)(long double complex z)
 {
-	return z;
+	return creall(z);
 }