optimize hot paths of putc with manual shrink-wrapping

this is the analog of commit dd8f02b7dce53d6b1c4282439f1636a2d63bee01,
but for putc.

src/stdio/fputc.c

@@ -1,10 +1,7 @@
-#include "stdio_impl.h"
+#include <stdio.h>
+#include "putc.h"
 
 int fputc(int c, FILE *f)
 {
-	if (f->lock < 0 || !__lockfile(f))
-		return putc_unlocked(c, f);
-	c = putc_unlocked(c, f);
-	__unlockfile(f);
-	return c;
+	return do_putc(c, f);
 }

src/stdio/putc.c

@@ -1,12 +1,9 @@
-#include "stdio_impl.h"
+#include <stdio.h>
+#include "putc.h"
 
 int putc(int c, FILE *f)
 {
-	if (f->lock < 0 || !__lockfile(f))
-		return putc_unlocked(c, f);
-	c = putc_unlocked(c, f);
-	__unlockfile(f);
-	return c;
+	return do_putc(c, f);
 }
 
 weak_alias(putc, _IO_putc);

src/stdio/putchar.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
+#include "putc.h"
 
 int putchar(int c)
 {
-	return fputc(c, stdout);
+	return do_putc(c, stdout);
 }