Merge branch 'en/make-libgit-a'

Instead of three library archives (one for git, one for reftable,
and one for xdiff), roll everything into a single libgit.a archive.
This would help later effort to FFI into Rust.

* en/make-libgit-a:
make: delete REFTABLE_LIB, add reftable to LIB_OBJS
make: delete XDIFF_LIB, add xdiff to LIB_OBJS

Makefile

···
 TEST_SHELL_PATH = $(SHELL_PATH)
 
 LIB_FILE = libgit.a
-XDIFF_LIB = xdiff/lib.a
-REFTABLE_LIB = reftable/libreftable.a
 ifdef DEBUG
 RUST_LIB = target/debug/libgitcore.a
 else
 RUST_LIB = target/release/libgitcore.a
 endif
 
-# xdiff and reftable libs may in turn depend on what is in libgit.a
-GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
+GITLIBS = common-main.o $(LIB_FILE)
 EXTLIBS =
 
 GIT_USER_AGENT = git/$(GIT_VERSION)
···
 LIB_OBJS += refs/packed-backend.o
 LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
+LIB_OBJS += reftable/basics.o
+LIB_OBJS += reftable/block.o
+LIB_OBJS += reftable/blocksource.o
+LIB_OBJS += reftable/error.o
+LIB_OBJS += reftable/fsck.o
+LIB_OBJS += reftable/iter.o
+LIB_OBJS += reftable/merged.o
+LIB_OBJS += reftable/pq.o
+LIB_OBJS += reftable/record.o
+LIB_OBJS += reftable/stack.o
+LIB_OBJS += reftable/system.o
+LIB_OBJS += reftable/table.o
+LIB_OBJS += reftable/tree.o
+LIB_OBJS += reftable/writer.o
 LIB_OBJS += remote.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o
···
 LIB_OBJS += ws.o
 LIB_OBJS += wt-status.o
 LIB_OBJS += xdiff-interface.o
+LIB_OBJS += xdiff/xdiffi.o
+LIB_OBJS += xdiff/xemit.o
+LIB_OBJS += xdiff/xhistogram.o
+LIB_OBJS += xdiff/xmerge.o
+LIB_OBJS += xdiff/xpatience.o
+LIB_OBJS += xdiff/xprepare.o
+LIB_OBJS += xdiff/xutils.o
 
 BUILTIN_OBJS += builtin/add.o
 BUILTIN_OBJS += builtin/am.o
···
 .PHONY: reconfigure # This is a convenience target.
 endif
 
-XDIFF_OBJS += xdiff/xdiffi.o
-XDIFF_OBJS += xdiff/xemit.o
-XDIFF_OBJS += xdiff/xhistogram.o
-XDIFF_OBJS += xdiff/xmerge.o
-XDIFF_OBJS += xdiff/xpatience.o
-XDIFF_OBJS += xdiff/xprepare.o
-XDIFF_OBJS += xdiff/xutils.o
-.PHONY: xdiff-objs
-xdiff-objs: $(XDIFF_OBJS)
-
-REFTABLE_OBJS += reftable/basics.o
-REFTABLE_OBJS += reftable/block.o
-REFTABLE_OBJS += reftable/blocksource.o
-REFTABLE_OBJS += reftable/error.o
-REFTABLE_OBJS += reftable/fsck.o
-REFTABLE_OBJS += reftable/iter.o
-REFTABLE_OBJS += reftable/merged.o
-REFTABLE_OBJS += reftable/pq.o
-REFTABLE_OBJS += reftable/record.o
-REFTABLE_OBJS += reftable/stack.o
-REFTABLE_OBJS += reftable/system.o
-REFTABLE_OBJS += reftable/table.o
-REFTABLE_OBJS += reftable/tree.o
-REFTABLE_OBJS += reftable/writer.o
-
 TEST_OBJS := $(patsubst %$X,%.o,$(TEST_PROGRAMS)) $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS))
 
 .PHONY: test-objs
···
 OBJECTS += $(SCALAR_OBJS)
 OBJECTS += $(PROGRAM_OBJS)
 OBJECTS += $(TEST_OBJS)
-OBJECTS += $(XDIFF_OBJS)
 OBJECTS += $(FUZZ_OBJS)
-OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
+OBJECTS += $(REFTABLE_TEST_OBJS)
 OBJECTS += $(UNIT_TEST_OBJS)
 OBJECTS += $(CLAR_TEST_OBJS)
 OBJECTS += $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
···
 
 .PHONY: rust
 rust: $(RUST_LIB)
-
-$(XDIFF_LIB): $(XDIFF_OBJS)
-	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
-
-$(REFTABLE_LIB): $(REFTABLE_OBJS)
-	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
 export DEFAULT_EDITOR DEFAULT_PAGER
 
···
 	$(RM) git.rc git.res
 	$(RM) $(OBJECTS)
 	$(RM) headless-git.o
-	$(RM) $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB)
+	$(RM) $(LIB_FILE)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS)
 	$(RM) $(TEST_PROGRAMS)
 	$(RM) $(FUZZ_PROGRAMS)
···
 
 LIBGIT_PUB_OBJS += contrib/libgit-sys/public_symbol_export.o
 LIBGIT_PUB_OBJS += libgit.a
-LIBGIT_PUB_OBJS += reftable/libreftable.a
-LIBGIT_PUB_OBJS += xdiff/lib.a
 
 LIBGIT_PARTIAL_EXPORT = contrib/libgit-sys/partial_symbol_export.o