silence a bunch of gcc warnings

docs/gudev/Makefile.am

@@ -21,7 +21,7 @@ DOC_MAIN_SGML_FILE=$(DOC_MODULE)-docs.xml
 # gtk-doc will search all .c & .h files beneath here for inline comments
 # documenting the functions and macros.
 # e.g. DOC_SOURCE_DIR=../../../gtk
-DOC_SOURCE_DIR=$(top_srcdir)/src/gudev
+DOC_SOURCE_DIR=$(top_srcdir)/src/gudev $(top_builddir)/src/gudev
 
 # Extra options to pass to gtkdoc-scangobj. Not normally needed.
 SCANGOBJ_OPTIONS=

src/detect-virt/detect-virt.c

@@ -115,7 +115,8 @@ static int parse_argv(int argc, char *argv[]) {
 
 int main(int argc, char *argv[]) {
         const char *id = NULL;
-        int retval, r;
+        int r;
+        int retval = EXIT_SUCCESS;
 
         /* This is mostly intended to be used for scripts which want
          * to detect whether we are being run in a virtualized

src/shared/cgroup-util.c

@@ -514,7 +514,7 @@ static const char *normalize_controller(const char *controller) {
 }
 
 static int join_path(const char *controller, const char *path, const char *suffix, char **fs) {
-        char *t;
+        char *t = NULL;
 
         if (!(controller || path))
                 return -EINVAL;

src/udev/udev-builtin.c

@@ -42,7 +42,7 @@ static const struct udev_builtin *builtins[] = {
 int udev_builtin_init(struct udev *udev)
 {
         unsigned int i;
-        int err;
+        int err = 0;
 
         for (i = 0; i < ELEMENTSOF(builtins); i++) {
                 if (builtins[i]->init) {