env: allow people to force envcrc building

For people who want to manually extract the embedded environment so that
it can be manually packed into the final u-boot image, add a config opt
to force building of the envcrc tool.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

README

@@ -2563,6 +2563,11 @@ The following definitions that deal with the placement and management
 of environment data (variable area); in general, we support the
 following configurations:
 
+- CONFIG_BUILD_ENVCRC:
+
+	Builds up envcrc with the target environment so that external utils
+	may easily extract it and embed it in final U-Boot images.
+
 - CONFIG_ENV_IS_IN_FLASH:
 
 	Define this if the environment is in flash memory.

common/env_embedded.c

@@ -44,7 +44,7 @@
  * Generate embedded environment table
  * inside U-Boot image, if needed.
  */
-#if defined(ENV_IS_EMBEDDED)
+#if defined(ENV_IS_EMBEDDED) || defined(CONFIG_BUILD_ENVCRC)
 /*
  * Only put the environment in it's own section when we are building
  * U-Boot proper.  The host based program "tools/envcrc" does not need

include/common.h

@@ -761,4 +761,9 @@ int cpu_release(int nr, int argc, char * const argv[]);
 #define ALIGN(x,a)		__ALIGN_MASK((x),(typeof(x))(a)-1)
 #define __ALIGN_MASK(x,mask)	(((x)+(mask))&~(mask))
 
+/* Pull in stuff for the build system */
+#ifdef DO_DEPS_ONLY
+# include <environment.h>
+#endif
+
 #endif	/* __COMMON_H_ */

tools/envcrc.c

@@ -60,6 +60,10 @@
 # endif
 #endif	/* CONFIG_ENV_IS_IN_FLASH */
 
+#if defined(ENV_IS_EMBEDDED) && !defined(CONFIG_BUILD_ENVCRC)
+# define CONFIG_BUILD_ENVCRC 1
+#endif
+
 #ifdef CONFIG_SYS_REDUNDAND_ENVIRONMENT
 # define ENV_HEADER_SIZE	(sizeof(uint32_t) + 1)
 #else
@@ -71,14 +75,14 @@
 
 extern uint32_t crc32 (uint32_t, const unsigned char *, unsigned int);
 
-#ifdef	ENV_IS_EMBEDDED
+#ifdef CONFIG_BUILD_ENVCRC
 extern unsigned int env_size;
 extern unsigned char environment;
-#endif	/* ENV_IS_EMBEDDED */
+#endif	/* CONFIG_BUILD_ENVCRC */
 
 int main (int argc, char **argv)
 {
-#ifdef	ENV_IS_EMBEDDED
+#ifdef CONFIG_BUILD_ENVCRC
 	unsigned char pad = 0x00;
 	uint32_t crc;
 	unsigned char *envptr = &environment,