build: support make help-overrides and make help-options

These provide only *part* of the make help output, and as a side
benefit shuffle the output into a somewhat better order.

Used by the upcoming configure script to avoid needlessly
reduplicating help text.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Reviewed-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

Makeconfig

@@ -14,7 +14,7 @@ CONFIG_MK = $(objdir)/config.mk
 #
 # Syntax: $(call make-override-help,var,help-string)
 define make-override-help
-help::
+help-overrides::
 	width=$$$$(printf '$(1)=[yes/no]' | wc -c); \
 	tabs="\t\t\t\t"; \
 	if [[ $$$${width} -gt 31 ]]; then \
@@ -144,7 +144,7 @@ $(CONFIG_MK):
 	echo 'CONFIGURED := yes' >> $(objdir)/config.mk
 	cat $(objdir)/.config/*.mk >> $(objdir)/config.mk 2>/dev/null || true
 
-help::
+help-overrides::
 	printf "Overrides for library and symbol searches:\n\n" >&2
 
 $(eval $(call check-symbol-rule,ELF_GETSHDRSTRNDX,elf_getshdrstrndx,elf))
@@ -163,5 +163,7 @@ $(eval $(call check-header-rule,DIS4,disassembler(0,0,0,NULL),dis-asm))
 $(eval $(call check-header-rule,INITDISINFO3,init_disassemble_info(NULL,NULL,NULL),dis-asm))
 $(eval $(call check-header-rule,INITDISINFO4,init_disassemble_info(NULL,NULL,NULL,NULL),dis-asm))
 
-help::
+help-overrides::
 	printf "\n" >&2
+
+help:: help-overrides

Makeoptions

@@ -11,15 +11,19 @@ coverage ?= no
 verbose ?= no
 libfuse2 ?= no
 
-help::
+help-options::
 	@printf "Options:\n\n" >&2
 	@printf "make debugging=yes [targets]\tDisable optimization to make debugger use easier\n" >&2
 	@printf "make coverage=yes [targets]\tTurn on coverage support in the testsuite\n" >&2
 	@printf "make verbose=yes [target]\tEnable verbose building\n" >&2
 	@printf "make dof_dbg=yes [targets]\tTurn on especially noisy DOF parser debugging\n\n" >&2
+
+help-dependencies::
 	@printf "Dependencies:\n\n" >&2
 	@printf "make libfuse2=yes [targets]\tBuild against libfuse 2 even if libfuse 3 is found\n\n" >&2
 
+help:: help-options help-dependencies
+
 ifneq ($(debugging),no)
 override CFLAGS += -O0 -g
 endif