Make RealEquals only compare the data bytes.

Fixes run/t/template_class_13_* regressions introduced in [r401].

dmd/expression.c

@@ -1498,7 +1498,7 @@ int RealEquals(real_t x1, real_t x2)
 	/* In some cases, the REALPAD bytes get garbage in them,
 	 * so be sure and ignore them.
 	 */
-	memcmp(&x1, &x2, sizeof(real_t)) == 0;
+	memcmp(&x1, &x2, REAL_T_SIZE - REAL_T_PAD) == 0;
 }
 
 int RealExp::equals(Object *o)

dmd/mars.h

@@ -213,6 +213,8 @@ typedef d_uns32			d_dchar;
 #include "d-gcc-real.h"
 #else
 typedef long double real_t;
+#define REAL_T_SIZE 12
+#define REAL_T_PAD 2
 #endif
 
 // Modify OutBuffer::writewchar to write the correct size of wchar