tools: move accounting tool from Documentation

Move accounting tool to tools and remove it from Documentation
Makefile. Update location information for this tool. Create a
new Makefile to build accounting. It can be built from top level
directory or from accounting directory:

Run make -C tools/accounting or cd tools/accounting; make

Acked-by: Jonathan Corbet <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

Documentation/Makefile

···
-subdir-y := accounting blackfin \
+subdir-y := blackfin \
 	laptops pcmcia

Documentation/accounting/Makefile

···
-# List of programs to build
-hostprogs-y := getdelays
-
-# Tell kbuild to always build the programs
-always := $(hostprogs-y)
-
-HOSTCFLAGS_getdelays.o += -I$(objtree)/usr/include

Documentation/accounting/delay-accounting.txt

···
 task of a thread group, the per-tgid statistics are also sent. More details
 are given in the taskstats interface description.
 
-The getdelays.c userspace utility in this directory allows simple commands to
-be run and the corresponding delay statistics to be displayed. It also serves
-as an example of using the taskstats interface.
+The getdelays.c userspace utility in tools/accounting directory allows simple
+commands to be run and the corresponding delay statistics to be displayed. It
+also serves as an example of using the taskstats interface.
 
 Usage
 -----

tools/accounting/Makefile

···
+CC := $(CROSS_COMPILE)gcc
+CFLAGS := -I../../usr/include
+
+PROGS := getdelays
+
+all: $(PROGS)
+
+clean:
+	rm -fr $(PROGS)