libutil: Implement zsh and bash autocompletion

Add functionality for generating autocompletion scripts,
allowing for tab completion of tool options for bash and zsh.

This functionality relies on reading the available options
from the util_opt struct at runtime.

The script generation happens on the build system.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Szabina Korbai <szkorbai@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

libutil/Makefile

@@ -1,13 +1,16 @@
 include ../common.mak
+include ../common_autocomp.mak
 
 lib := libutil.a
 
-sources := $(filter-out %_example.c,$(wildcard *.c))
+sources := $(filter-out %_example.c %_host.c, $(wildcard *.c))
 objects := $(patsubst %.c,%.o,$(sources))
 
+autocomp-object := util_autocomp_host.o
+
 examples := $(patsubst %.c,%,$(wildcard *_example.c))
 
-all: $(lib)
+all: $(lib) $(autocomp-object)
 examples: $(examples)
 
 $(examples): %: %.o $(lib)