makefile: allow platform files with gnu sed

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Makefile

@@ -6,14 +6,13 @@ MANDIR ?= $(PREFIX)/share/man
 
 PLATFORMFILE := src/platform/$(shell uname | cut -d _ -f 1 | tr '[:upper:]' '[:lower:]').sh
 
-.PHONY: install uninstall install-pass
+.PHONY: install uninstall install-common
 
 all:
 	@echo "Password store is a shell script, so there is nothing to do. Try \"make install\" instead."
 
-install-pass:
+install-common:
 	@mkdir -p "$(DESTDIR)$(BINDIR)" "$(DESTDIR)$(LIBDIR)" "$(DESTDIR)$(MANDIR)/man1" "$(DESTDIR)$(PREFIX)/share/bash-completion/completions/"
-	@install -m 0755 -v src/password-store.sh "$(DESTDIR)$(BINDIR)/pass"
 	@install -m 0644 -v man/pass.1 "$(DESTDIR)$(MANDIR)/man1/pass.1"
 	@install -m 0644 -v src/completion/pass.bash-completion "$(DESTDIR)$(PREFIX)/share/bash-completion/completions/pass"
 
@@ -24,12 +23,14 @@ install-pass:
 #	@install -m 0644 -v src/completion/pass.fish-completion "$(DESTDIR)$(PREFIX)/share/fish/completions/pass.fish"
 
 ifneq ($(strip $(wildcard $(PLATFORMFILE))),)
-install: install-pass
+install: install-common
 	@install -m 0644 -v "$(PLATFORMFILE)" "$(DESTDIR)$(LIBDIR)/password-store.platform.sh"
-#	The -i "" doesn't work on GNU, where the extra argument isn't needed. Fortuantely, platform file is for non-GNU only.
-	sed -i "" 's:.*platform-defined-functions.*:source $(DESTDIR)$(LIBDIR)/password-store.platform.sh:' "$(DESTDIR)$(BINDIR)/pass"
+	@mkdir -p -v "$(DESTDIR)$(BINDIR)/"
+	sed 's:.*platform-defined-functions.*:source $(DESTDIR)$(LIBDIR)/password-store.platform.sh:' src/password-store.sh > "$(DESTDIR)$(BINDIR)/pass"
+	@chmod 0755 "$(DESTDIR)$(BINDIR)/pass"
 else
-install: install-pass
+install: install-common
+	@install -m 0755 -v src/password-store.sh "$(DESTDIR)$(BINDIR)/pass"
 endif
 
 uninstall: