Fix cppcheck warnings in color lerp

Author: ankith26

src_c/color.c

@@ -47,12 +47,16 @@
 
 #include <ctype.h>
 
+static inline double
+pg_round(double d)
+{
 #if (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L) && \
     !defined(round)
-#define pg_round(d) (((d < 0) ? (ceil((d) - 0.5)) : (floor((d) + 0.5))))
+    return (((d < 0) ? (ceil((d)-0.5)) : (floor((d) + 0.5))));
 #else
-#define pg_round(d) round(d)
+    return round(d);
 #endif
+}
 
 typedef enum { TRISTATE_SUCCESS, TRISTATE_FAIL, TRISTATE_ERROR } tristate;
 
@@ -813,10 +817,10 @@ _color_lerp(pgColorObject *self, PyObject *args, PyObject *kw)
         return RAISE(PyExc_ValueError, "Argument 2 must be in range [0, 1]");
     }
 
-    new_rgba[0] = (Uint8)pg_round(self->data[0] * (1 - amt) + rgba[0] * amt);
-    new_rgba[1] = (Uint8)pg_round(self->data[1] * (1 - amt) + rgba[1] * amt);
-    new_rgba[2] = (Uint8)pg_round(self->data[2] * (1 - amt) + rgba[2] * amt);
-    new_rgba[3] = (Uint8)pg_round(self->data[3] * (1 - amt) + rgba[3] * amt);
+    for (int i = 0; i < 4; i++) {
+        new_rgba[i] =
+            (Uint8)pg_round(self->data[i] * (1 - amt) + rgba[i] * amt);
+    }
 
     return (PyObject *)_color_new_internal(Py_TYPE(self), new_rgba);
 }