GNUMakefile: install libstdbuf

Use external libstdbuf.so when building with make, as embedding the library
is only needed to work around "cargo install" limitations with shared libraries.

Also change default installation directory to /usr/local/libexec/coreutils/ for consistency
with GNU coreutils

Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>

GNUmakefile

@@ -33,6 +33,9 @@ PREFIX ?= /usr/local
 DESTDIR ?=
 BINDIR ?= $(PREFIX)/bin
 DATAROOTDIR ?= $(PREFIX)/share
+LIBSTDBUF_DIR ?= $(PREFIX)/libexec/coreutils
+# Export variable so that it is used during the build
+export LIBSTDBUF_DIR
 
 INSTALLDIR_BIN=$(DESTDIR)$(BINDIR)
 
@@ -199,6 +202,8 @@ ifneq ($(OS),Windows_NT)
 	PROGS := $(PROGS) $(UNIX_PROGS)
 # Build the selinux command even if not on the system
 	PROGS := $(PROGS) $(SELINUX_PROGS)
+# Always use external libstdbuf when building with make (Unix only)
+	CARGOFLAGS += --features feat_external_libstdbuf
 endif
 
 UTILS ?= $(PROGS)
@@ -438,6 +443,10 @@ endif
 
 install: build install-manpages install-completions install-locales
 	mkdir -p $(INSTALLDIR_BIN)
+ifneq ($(OS),Windows_NT)
+	mkdir -p $(DESTDIR)$(LIBSTDBUF_DIR)
+	$(INSTALL) -m 755 $(BUILDDIR)/deps/libstdbuf* $(DESTDIR)$(LIBSTDBUF_DIR)/
+endif
 ifeq (${MULTICALL}, y)
 	$(INSTALL) $(BUILDDIR)/coreutils $(INSTALLDIR_BIN)/$(PROG_PREFIX)coreutils
 	$(foreach prog, $(filter-out coreutils, $(INSTALLEES)), \
@@ -452,6 +461,10 @@ else
 endif
 
 uninstall:
+ifneq ($(OS),Windows_NT)
+	rm -f $(DESTDIR)$(LIBSTDBUF_DIR)/libstdbuf*
+	-rmdir $(DESTDIR)$(LIBSTDBUF_DIR) 2>/dev/null || true
+endif
 ifeq (${MULTICALL}, y)
 	rm -f $(addprefix $(INSTALLDIR_BIN)/,$(PROG_PREFIX)coreutils)
 endif