[source] build: fix the toolchain rebuild check

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/f44ae19e1566410b75de5039071a42a0f3ade949

commit f44ae19e1566410b75de5039071a42a0f3ade949
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Thu Feb 16 07:43:27 2017 +0100

    build: fix the toolchain rebuild check
    
    - Check for changes in toolchain/ only
    - Only replace the stamp file if it was changed
    - Fix dependencies for staging dir prepare
    - Move the stamp file to TOOLCHAIN_DIR
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 toolchain/Makefile | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/toolchain/Makefile b/toolchain/Makefile
index 34abda2..7a9730f 100644
--- a/toolchain/Makefile
+++ b/toolchain/Makefile
@@ -70,15 +70,15 @@ endif
 endif
 
 ifdef CONFIG_BUILDBOT
-  $(STAGING_DIR)/.toolchain_ver_check: $(TMP_DIR)/.build
-	cd "$(TOPDIR)"; git log --format=%h -1 > $(TMP_DIR)/.toolchain_ver_check
-	cmp -s $(TMP_DIR)/.toolchain_ver_check $@ || \
-		rm -rf $(BUILD_DIR) $(STAGING_DIR) $(TOOLCHAIN_DIR) $(BUILD_DIR_TOOLCHAIN)
-	mkdir -p $(STAGING_DIR)
-	mv $(TMP_DIR)/.toolchain_ver_check $@
+  $(TOOLCHAIN_DIR)/stamp/.ver_check: $(TMP_DIR)/.build
+	cd "$(TOPDIR)"; git log --format=%h -1 toolchain > $(TMP_DIR)/.ver_check
+	cmp -s $(TMP_DIR)/.ver_check $@ || { \
+		rm -rf $(BUILD_DIR) $(STAGING_DIR) $(TOOLCHAIN_DIR) $(BUILD_DIR_TOOLCHAIN); \
+		mkdir -p $(TOOLCHAIN_DIR)/stamp; \
+		mv $(TMP_DIR)/.ver_check $@; \
+	}
 
-$(STAGING_DIR)/.prepared: $(STAGING_DIR)/.toolchain_ver_check
-$(TOOLCHAIN_DIR)/stamp/.gcc-initial_installed: $(STAGING_DIR)/.prepared
+$(TOOLCHAIN_DIR)/info.mk $(STAGING_DIR)/.prepared: $(TOOLCHAIN_DIR)/stamp/.ver_check
 endif
 
 # prerequisites for the individual targets