Makefile.inc: Add build targets for IASL & Clang

- Add specific build targets for IASL & CLANG and help for those targets
- Consolidate tool target .PHONY entries

Change-Id: If2960d75310495d9e486b3a08808463a2ff0c644
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12541
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

Makefile

@@ -93,8 +93,8 @@ DOXYGEN_OUTPUT_DIR := doxygen
 
 all: real-all
 
-help::
-	@echo  '*** coreboot platform ***'
+help_coreboot help::
+	@echo  '*** coreboot platform targets ***'
 	@echo  '  Use "make [target] V=1" for extra build debug information'
 	@echo  '  all                   - Build coreboot'
 	@echo  '  clean                 - Remove coreboot build artifacts'
@@ -121,7 +121,7 @@ ifeq ($(strip $(HAVE_DOTCONFIG)),)
 NOCOMPILE:=1
 endif
 ifneq ($(MAKECMDGOALS),)
-ifneq ($(filter %config %clean cross% lint% what-jenkins-does,$(MAKECMDGOALS)),)
+ifneq ($(filter %config %clean cross% clang iasl lint% what-jenkins-does,$(MAKECMDGOALS)),)
 NOCOMPILE:=1
 endif
 ifeq ($(MAKECMDGOALS), %clean)