notmuch.desktop: move under emacs as notmuch-emacs-mua.desktop

The notmuch.desktop file is part of notmuch-emacs. Move it under
emacs, and rename as notmuch-emacs-mua.desktop to reflect this.

Makefile.local

@@ -274,11 +274,6 @@ ifeq ($(WITH_EMACS), 1)
 endif
 endif
 
-.PHONY: install-desktop
-install-desktop:
-	mkdir -p "$(DESTDIR)$(desktop_dir)"
-	desktop-file-install --mode 0644 --dir "$(DESTDIR)$(desktop_dir)" notmuch.desktop
-
 SRCS  := $(SRCS) $(notmuch_client_srcs)
 CLEAN := $(CLEAN) notmuch notmuch-shared $(notmuch_client_modules)
 CLEAN := $(CLEAN) version.stamp notmuch-*.tar.gz.tmp

emacs/Makefile.local

@@ -39,6 +39,7 @@ all: $(dir)/notmuch-pkg.el
 install-emacs: $(dir)/notmuch-pkg.el
 
 emacs_mua := $(dir)/notmuch-emacs-mua
+emacs_mua_desktop := $(dir)/notmuch-emacs-mua.desktop
 
 emacs_images := \
 	$(srcdir)/$(dir)/notmuch-logo.png
@@ -106,4 +107,9 @@ endif
 	mkdir -p "$(DESTDIR)$(prefix)/bin/"
 	install $(emacs_mua) "$(DESTDIR)$(prefix)/bin"
 
+.PHONY: install-desktop
+install-desktop:
+	mkdir -p "$(DESTDIR)$(desktop_dir)"
+	desktop-file-install --mode 0644 --dir "$(DESTDIR)$(desktop_dir)" $(emacs_mua_desktop)
+
 CLEAN := $(CLEAN) $(emacs_bytecode) $(dir)/notmuch-version.el $(dir)/notmuch-pkg.el