x86, setup: enable early console output from the decompressor

This enables the decompressor output to be seen on the serial console.
Most of the code is shared with the regular boot code.

We could add printf to the decompressor if needed, but currently there
is no sufficiently compelling user.

-v2: define BOOT_BOOT_H to avoid include boot.h
-v3: early_serial_base need to be static in misc.c ?
-v4: create seperate string.c printf.c cmdline.c early_serial_console.c
     after hpa's patch that allow global variables in compressed/misc stage
-v5: remove printf.c related

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/boot/main.c

@@ -132,6 +132,8 @@ void main(void)
 
 	/* Initialize the early-boot console */
 	console_init();
+	if (cmdline_find_option_bool("debug"))
+		puts("early console in setup code\n");
 
 	/* End of heap check */
 	init_heap();
@@ -171,10 +173,6 @@ void main(void)
 	/* Set the video mode */
 	set_video();
 
-	/* Parse command line for 'quiet' and pass it to decompressor. */
-	if (cmdline_find_option_bool("quiet"))
-		boot_params.hdr.loadflags |= QUIET_FLAG;
-
 	/* Do the last things and invoke protected mode */
 	go_to_protected_mode();
 }