Bug 1114745 - remove dead IS_ASAN defines from automation-build.mk; r=ted

Nothing uses IS_ASAN, likely because all relevant uses have been ported
over to mozinfo.

build/automation-build.mk

@@ -54,12 +54,6 @@ else
 AUTOMATION_PPARGS += -DCRASHREPORTER=0
 endif
 
-ifdef MOZ_ASAN
-AUTOMATION_PPARGS += -DIS_ASAN=1
-else
-AUTOMATION_PPARGS += -DIS_ASAN=0
-endif
-
 automation.py: $(MOZILLA_DIR)/build/automation.py.in $(MOZILLA_DIR)/build/automation-build.mk
 	$(call py_action,preprocessor, \
 	$(AUTOMATION_PPARGS) $(DEFINES) $(ACDEFINES) $< -o $@)