Don't cast the return value of malloc/realloc

This patch has been generated by the following Coccinelle semantic
patch:

// Don't cast the return value of malloc/realloc.
//
// Casting the return value of malloc/realloc only stands to hide
// errors.

@@
type T;
expression E1, E2;
@@
- (T)
(
_mesa_align_calloc(E1, E2)
|
_mesa_align_malloc(E1, E2)
|
calloc(E1, E2)
|
malloc(E1)
|
realloc(E1, E2)
)

src/glx/glxcmds.c

@@ -2454,7 +2454,7 @@ _X_HIDDEN char *
 __glXstrdup(const char *str)
 {
    char *copy;
-   copy = (char *) malloc(strlen(str) + 1);
+   copy = malloc(strlen(str) + 1);
    if (!copy)
       return NULL;
    strcpy(copy, str);