Modify several tests to use test-skeleton.c

These tests were skipped by the use-test-skeleton conversion done in
commit 29955b5d because they did not have an `int main (void)'
declaration. Instead their `main' functions were declared with arguments
(i.e. argc, argv) even though they didn't use them.

Remove these arguments and include the test skeleton in these tests.

stdio-common/test-fwrite.c

@@ -1,8 +1,8 @@
 #include <stdio.h>
 #include <string.h>
 
-int
-main (int argc, char *argv[])
+static int
+do_test (void)
 {
   FILE *f = tmpfile ();
   char obuf[99999], ibuf[sizeof obuf];
@@ -66,3 +66,6 @@ There is absolutely no warranty for GDB; type \"show warranty\" for details.\n\
   puts ("Test succeeded.");
   return 0;
 }
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"

stdio-common/tst-ferror.c

@@ -1,7 +1,7 @@
 #include <stdio.h>
 
-int
-main (int argc, char *argv[])
+static int
+do_test (void)
 {
   char buf[100];
   int result = 0;
@@ -39,3 +39,6 @@ main (int argc, char *argv[])
     }
   return result;
 }
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"

stdio-common/tst-printf.c

@@ -132,8 +132,8 @@ fp_test (void)
   printf("%-10s\n", (char *) NULL);
 }
 
-int
-main (int argc, char *argv[])
+static int
+do_test (void)
 {
   static char shortstr[] = "Hi, Z.";
   static char longstr[] = "Good morning, Doctor Chandra.  This is Hal.  \
@@ -393,3 +393,6 @@ rfg3 (void)
     printf ("got: '%s', expected: '%s'\n", buf,
 	    "   12345  1234    11145401322     321.765432   3.217654e+02   5    test-string");
 }
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"

stdio-common/tst-printfsz.c

@@ -7,8 +7,8 @@
 #define V       12345678.12345678
 
 
-int
-main (int argc, char *argv[])
+static int
+do_test (void)
 {
   char buf[1024];
   int result = 0;
@@ -76,3 +76,6 @@ main (int argc, char *argv[])
 
   return result;
 }
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"