Use safer allocation macros

Use of these macros, apart from the benefits mentioned in the commit
that adds the macros, has some other good side effects:

-  Consistency in getting the size of the object from sizeof(type),
   instead of a mix of sizeof(type) sometimes and sizeof(*p) other
   times.

-  More readable code: no casts, and no sizeof(), so also shorter lines
   that we don't need to cut.

-  Consistency in using array allocation calls for allocations of arrays
   of objects, even when the object size is 1.

Cc: Valentin V. Bartenev <vbartenev@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

libmisc/setupenv.c

@@ -20,6 +20,8 @@
 #include <sys/stat.h>
 #include <stdio.h>
 #include <ctype.h>
+
+#include "alloc.h"
 #include "prototypes.h"
 #include "defines.h"
 #include <pwd.h>
@@ -34,7 +36,7 @@ addenv_path (const char *varname, const char *dirname, const char *filename)
 	size_t len = strlen (dirname) + strlen (filename) + 2;
 	int wlen;
 
-	buf = xmalloc (len);
+	buf = XMALLOCARRAY (len, char);
 	wlen = snprintf (buf, len, "%s/%s", dirname, filename);
 	assert (wlen == (int) len - 1);