Make build deterministic and do not rebuild on release2 (#729)

* sort dbc files to make linking deterministic

* touch all files on release2 checkout to prevent rebuild

launch_chffrplus.sh

@@ -13,9 +13,16 @@ fi
 function launch {
   # apply update
   if [ "$(git rev-parse HEAD)" != "$(git rev-parse @{u})" ]; then
-     git reset --hard @{u} &&
-     git clean -xdf &&
-     exec "${BASH_SOURCE[0]}"
+    git reset --hard @{u} &&
+    git clean -xdf &&
+
+    # Touch all files on release2 after checkout to prevent rebuild
+    BRANCH=$(git rev-parse --abbrev-ref HEAD)
+    if [[ "$BRANCH" == "release2" ]]; then
+        touch **
+    fi
+
+    exec "${BASH_SOURCE[0]}"
   fi
 
   # no cpu rationing for now

selfdrive/can/Makefile

@@ -38,7 +38,7 @@ OBJDIR = obj
 
 OPENDBC_PATH := $(shell python2 -c 'import opendbc; print opendbc.DBC_PATH')
 
-DBC_SOURCES := $(wildcard $(OPENDBC_PATH)/*.dbc)
+DBC_SOURCES := $(sort $(wildcard $(OPENDBC_PATH)/*.dbc))
 DBC_OBJS := $(patsubst $(OPENDBC_PATH)/%.dbc,$(OBJDIR)/%.o,$(DBC_SOURCES))
 DBC_CCS := $(patsubst $(OPENDBC_PATH)/%.dbc,dbc_out/%.cc,$(DBC_SOURCES))
 .SECONDARY: $(DBC_CCS)