importd: try to minimize confusion by renaming "systemd-import" binary to "systemd-pull"

This way "systemd-importd" is the daemon that uses "systemd-pull" as
backend worker.

Makefile.am

@@ -5273,24 +5273,21 @@ if HAVE_GCRYPT
 
 rootlibexec_PROGRAMS += \
 	systemd-importd \
-	systemd-import
+	systemd-pull
 
 systemd_importd_SOURCES = \
-	src/import/importd.c \
-	src/import/importd.h
+	src/import/importd.c
 
 systemd_importd_CFLAGS = \
 	$(AM_CFLAGS) \
-	-D SYSTEMD_IMPORT_PATH=\"$(rootlibexecdir)/systemd-import\" \
-	-D VENDOR_KEYRING_PATH=\"$(rootlibexecdir)/import-pubring.gpg\" \
-	-D USER_KEYRING_PATH=\"$(pkgsysconfdir)/import-pubring.gpg\"
+	-D SYSTEMD_PULL_PATH=\"$(rootlibexecdir)/systemd-import\"
 
 systemd_importd_LDADD = \
 	libsystemd-internal.la \
 	libsystemd-shared.la
 
-systemd_import_SOURCES = \
-	src/import/import.c \
+systemd_pull_SOURCES = \
+	src/import/pull.c \
 	src/import/import-raw.c \
 	src/import/import-raw.h \
 	src/import/import-tar.c \
@@ -5308,7 +5305,7 @@ systemd_import_SOURCES = \
 	src/import/qcow2-util.c \
 	src/import/qcow2-util.h
 
-systemd_import_CFLAGS = \
+systemd_pull_CFLAGS = \
 	$(AM_CFLAGS) \
 	$(LIBCURL_CFLAGS) \
 	$(XZ_CFLAGS) \
@@ -5317,7 +5314,7 @@ systemd_import_CFLAGS = \
 	-D VENDOR_KEYRING_PATH=\"$(rootlibexecdir)/import-pubring.gpg\" \
 	-D USER_KEYRING_PATH=\"$(pkgsysconfdir)/import-pubring.gpg\"
 
-systemd_import_LDADD = \
+systemd_pull_LDADD = \
 	libsystemd-internal.la \
 	libsystemd-label.la \
 	libsystemd-shared.la \

src/import/importd.c

@@ -342,7 +342,7 @@ static int transfer_start(Transfer *t) {
                 return -errno;
         if (t->pid == 0) {
                 const char *cmd[] = {
-                        "systemd-import",
+                        "systemd-pull",
                         t->type == TRANSFER_TAR ? "pull-tar" :
                         t->type == TRANSFER_RAW ? "pull-raw" :
                                                       "pull-dkr",
@@ -413,7 +413,7 @@ static int transfer_start(Transfer *t) {
                         cmd[k++] = t->local;
                 cmd[k] = NULL;
 
-                execv(SYSTEMD_IMPORT_PATH, (char * const *) cmd);
+                execv(SYSTEMD_PULL_PATH, (char * const *) cmd);
                 log_error_errno(errno, "Failed to execute import tool: %m");
                 _exit(EXIT_FAILURE);
         }