Merge branch 'ab/make-optim-noop'

Makefile refactoring with a bit of suffixes rule stripping to
optimize the runtime overhead.

* ab/make-optim-noop:
  Makefiles: add and use wildcard "mkdir -p" template
  Makefile: add "$(QUIET)" boilerplate to shared.mak
  Makefile: move $(comma), $(empty) and $(space) to shared.mak
  Makefile: move ".SUFFIXES" rule to shared.mak
  Makefile: define $(LIB_H) in terms of $(FIND_SOURCE_FILES)
  Makefile: disable GNU make built-in wildcard rules
  Makefiles: add "shared.mak", move ".DELETE_ON_ERROR" to it
  scalar Makefile: use "The default target of..." pattern

contrib/scalar/Makefile

@@ -1,18 +1,8 @@
-QUIET_SUBDIR0  = +$(MAKE) -C # space to separate -C and subdir
-QUIET_SUBDIR1  =
+# The default target of this Makefile is...
+all::
 
-ifneq ($(findstring s,$(MAKEFLAGS)),s)
-ifndef V
-	QUIET_GEN      = @echo '   ' GEN $@;
-	QUIET_SUBDIR0  = +@subdir=
-	QUIET_SUBDIR1  = ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \
-			 $(MAKE) $(PRINT_DIR) -C $$subdir
-else
-	export V
-endif
-endif
-
-all:
+# Import tree-wide shared Makefile behavior and libraries
+include ../../shared.mak
 
 include ../../config.mak.uname
 -include ../../config.mak.autogen

contrib/scalar/t/Makefile

@@ -1,3 +1,6 @@
+# Import tree-wide shared Makefile behavior and libraries
+include ../../../shared.mak
+
 # Run scalar tests
 #
 # Copyright (c) 2005,2021 Junio C Hamano, Johannes Schindelin