Check whether we have -lusb-1.0 and it has libusb_init().

Don't just check for the libusb header file - apparently at least some
Linux distributions can't install both the 32-bit and 64-bit developer
versions of the libusb library, so you might have the libusb header, and
the library for one bit-width, but not the library for the other
bit-width, so the configure would succeed for the other bit-width but
the build would fail.

configure

@@ -8124,8 +8124,43 @@ fi
 if test "x$enable_canusb" != "xno" ; then
 		case "$host_os" in
 	linux*)
-		ac_fn_c_check_header_mongrel "$LINENO" "libusb-1.0/libusb.h" "ac_cv_header_libusb_1_0_libusb_h" "$ac_includes_default"
-if test "x$ac_cv_header_libusb_1_0_libusb_h" = xyes; then :
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libusb_init in -lusb-1.0" >&5
+$as_echo_n "checking for libusb_init in -lusb-1.0... " >&6; }
+if ${ac_cv_lib_usb_1_0_libusb_init+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lusb-1.0  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char libusb_init ();
+int
+main ()
+{
+return libusb_init ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_usb_1_0_libusb_init=yes
+else
+  ac_cv_lib_usb_1_0_libusb_init=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_usb_1_0_libusb_init" >&5
+$as_echo "$ac_cv_lib_usb_1_0_libusb_init" >&6; }
+if test "x$ac_cv_lib_usb_1_0_libusb_init" = xyes; then :
 
 
 $as_echo "#define PCAP_SUPPORT_CANUSB 1" >>confdefs.h
@@ -8141,7 +8176,6 @@ $as_echo "$as_me: canusb sniffing is not supported; install libusb1.0 lib devel
 
 fi
 
-
 		;;
 	*)
 		{ $as_echo "$as_me:${as_lineno-$LINENO}: no canusb support implemented for $host_os" >&5

configure.in

@@ -1528,7 +1528,7 @@ if test "x$enable_canusb" != "xno" ; then
 	dnl check for canusb support
 	case "$host_os" in
 	linux*)
-		AC_CHECK_HEADER(libusb-1.0/libusb.h,
+		AC_CHECK_LIB(usb-1.0, libusb_init,
 		[
 		    AC_DEFINE(PCAP_SUPPORT_CANUSB, 1, [target host supports canusb])
 		    CANUSB_SRC=pcap-canusb-linux.c