fix bug resulting from equally named files

the local vector.o files shadowed the ../cm3/vector.c from VPATH,
resulting in empty reset vectors.

lib/dispatch/vector_chipset.c

@@ -0,0 +1,11 @@
+#if defined(STM32F4)
+#	include "../stm32/f4/vector_chipset.c"
+
+#elif defined(LPC43XX)
+#	include "../lpc43xx/vector_chipset.c"
+
+#else
+
+static void pre_main(void) {}
+
+#endif