Merge branch 'jc/make-dedup-ls-files-output'

A "ls-files" that emulates "find" to enumerate files in the working
tree resulted in duplicated Makefile rules that caused the build to
issue an unnecessary warning during a trial build after merge
conflicts are resolved in working tree *.h files but before the
resolved results are added to the index.  This has been corrected.

* jc/make-dedup-ls-files-output:
  Makefile: dedup list of files obtained from ls-files
diff --git a/Makefile b/Makefile
index af24787..6d433f8 100644
--- a/Makefile
+++ b/Makefile
@@ -817,12 +817,12 @@
 
 GENERATED_H += command-list.h
 
-LIB_H := $(shell git ls-files '*.h' ':!t/' ':!Documentation/' 2>/dev/null || \
+LIB_H := $(sort $(shell git ls-files '*.h' ':!t/' ':!Documentation/' 2>/dev/null || \
 	$(FIND) . \
 	-name .git -prune -o \
 	-name t -prune -o \
 	-name Documentation -prune -o \
-	-name '*.h' -print)
+	-name '*.h' -print))
 
 LIB_OBJS += abspath.o
 LIB_OBJS += advice.o