introduce bb_putchar(). saves ~1800 on uclibc (less on glibc).

diff --git a/editors/ed.c b/editors/ed.c
index cd3836a..31185d9 100644
--- a/editors/ed.c
+++ b/editors/ed.c
@@ -853,14 +853,14 @@
 				ch &= 0x7f;
 			}
 			if (ch < ' ') {
-				fputc('^', stdout);
+				bb_putchar('^');
 				ch += '@';
 			}
 			if (ch == 0x7f) {
-				fputc('^', stdout);
+				bb_putchar('^');
 				ch = '?';
 			}
-			fputc(ch, stdout);
+			bb_putchar(ch);
 		}
 
 		fputs("$\n", stdout);