cmd: rework "license" command

The previous commit ("add a new command to show .config contents")
improves the basic infrastructure of "embed a compressed file into
the U-Boot image, and print it by a command".  The same pattern for
the "license" command.

This commit reworks the command to improve the following:

[1] Improve log style

Kbuild style log

  GZIP    cmd/license_data.gz
  CHK     cmd/license_data_gz.h
  UPD     cmd/license_data_gz.h
  CHK     cmd/license_data_size.h
  UPD     cmd/license_data_size.h

instead of the bare Make log:

cat ./Licenses/gpl-2.0.txt | gzip -9 -c | \
		tools/bin2header license_gzip > ./include/license.h

[2] Collect related code into the "cmd" directory

Prior to this commit, the license.h was created by tools/Makefile,
placed under the "include" directory, included from cmd/license.c,
and deleted by the top-level Makefile.  It is not a good idea to
scatter related code.

[3] Drop the fixed-malloc size LICENSE_MAX

Just allocate the minimum required size of buffer because we know
the size of the original gpl-2.0.txt.

[4] Fix more issues

Terminate the buffer with zero to prevent puts() from over-running.
Add "static" to do_license.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/Makefile b/tools/Makefile
index f5ac631..cbccd4a 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -32,7 +32,6 @@
 
 hostprogs-$(CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER) += atmel_pmecc_params
 
-hostprogs-$(CONFIG_CMD_LICENSE) += bin2header
 hostprogs-$(CONFIG_LCD_LOGO) += bmp_logo
 hostprogs-$(CONFIG_VIDEO_LOGO) += bmp_logo
 HOSTCFLAGS_bmp_logo.o := -pedantic
@@ -233,10 +232,6 @@
 
 endif # !LOGO_BMP
 
-# Generated gziped GPL-2.0 license text
-LICENSE_H = $(objtree)/include/license.h
-LICENSE-$(CONFIG_CMD_LICENSE) += $(LICENSE_H)
-
 #
 # Use native tools and options
 # Define __KERNEL_STRICT_NAMES to prevent typedef overlaps
@@ -251,7 +246,7 @@
 		-D__KERNEL_STRICT_NAMES \
 		-D_GNU_SOURCE
 
-__build:	$(LOGO-y) $(LICENSE-y)
+__build:	$(LOGO-y)
 
 $(LOGO_H):	$(obj)/bmp_logo $(LOGO_BMP)
 	$(obj)/bmp_logo --gen-info $(LOGO_BMP) > $@
@@ -259,10 +254,6 @@
 $(LOGO_DATA_H):	$(obj)/bmp_logo $(LOGO_BMP)
 	$(obj)/bmp_logo --gen-data $(LOGO_BMP) > $@
 
-$(LICENSE_H): $(obj)/bin2header $(srctree)/Licenses/gpl-2.0.txt
-	cat $(srctree)/Licenses/gpl-2.0.txt | gzip -9 -c | \
-		$(obj)/bin2header license_gzip > $(LICENSE_H)
-
 # Let clean descend into subdirs
 subdir- += env