[Buildroot] [PATCH RESEND] core: enhance printvars for variables with newlines

[Stefan Becker <chemobejk@gmail.com>]

If the variable content has newlines in it then the currently dumped
content can't be fed again to GNU make. Add the option DEFINE_VARS which
causes the variables to be dumped using

   define VAR
   ... line 1 ...
   ... line 2 ...
   ...
   endef

Updated the manual accordingly.

Signed-off-by: Stefan Becker <chemobejk@gmail.com>
---
 Makefile                  | 10 +++++++---
 docs/manual/make-tips.txt | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 0724f28f45..3e27195de0 100644
--- a/Makefile
+++ b/Makefile
@@ -974,9 +974,13 @@ printvars:
 		$(sort $(if $(VARS),$(filter $(VARS),$(.VARIABLES)),$(.VARIABLES))), \
 		$(if $(filter-out environment% default automatic, \
 				$(origin $V)), \
-		$(if $(QUOTED_VARS),\
-			$(info $V='$(subst ','\'',$(if $(RAW_VARS),$(value $V),$($V)))'), \
-			$(info $V=$(if $(RAW_VARS),$(value $V),$($V))))))
+		$(if $(DEFINE_VARS), \
+			$(info define $V) \
+			$(info $(if $(RAW_VARS),$(value $V),$($V))) \
+			$(info endef), \
+			$(if $(QUOTED_VARS),\
+				$(info $V='$(subst ','\'',$(if $(RAW_VARS),$(value $V),$($V)))'), \
+				$(info $V=$(if $(RAW_VARS),$(value $V),$($V)))))))
 # ' Syntax colouring...
 
 .PHONY: clean
diff --git a/docs/manual/make-tips.txt b/docs/manual/make-tips.txt
index ea1d825bef..ba87e5d873 100644
--- a/docs/manual/make-tips.txt
+++ b/docs/manual/make-tips.txt
@@ -92,6 +92,8 @@ It is possible to tweak the output using some variables:
 
 - +VARS+ will limit the listing to variables which names match the
   specified make-pattern
+- +DEFINE_VARS+, if set to +YES+, will use define...endef to preserve
+  newlines in the value
 - +QUOTED_VARS+, if set to +YES+, will single-quote the value
 - +RAW_VARS+, if set to +YES+, will print the unexpanded value
 
@@ -106,6 +108,24 @@ For example:
  BUSYBOX_RDEPENDENCIES=ncurses util-linux
 ----
 
+----
+ $ make -s printvars VARS=BUSYBOX_%DEPENDENCIES DEFINE_VARS=YES
+ define BUSYBOX_DEPENDENCIES
+ skeleton toolchain
+ endef
+ define BUSYBOX_FINAL_ALL_DEPENDENCIES
+ skeleton toolchain
+ endef
+ define BUSYBOX_FINAL_DEPENDENCIES
+ skeleton toolchain
+ endef
+ define BUSYBOX_FINAL_PATCH_DEPENDENCIES
+ endef
+ define BUSYBOX_RDEPENDENCIES
+ ncurses util-linux'linux-pam skeleton toolchain host-skeleton host-ccache
+ endef
+----
+
 ----
  $ make -s printvars VARS=BUSYBOX_%DEPENDENCIES QUOTED_VARS=YES
  BUSYBOX_DEPENDENCIES='skeleton toolchain'
-- 
2.14.3