completing dispatch

the LM3S irq list was previously unused as it was missing in the
dispatch files; now it got added. (before HEAD^, it wouldn't have made
any difference because the discriminating constant wasn't defined
anyway)

also, this enhances the warning messages

include/libopencm3/dispatch/nvic.h

@@ -11,8 +11,11 @@
 #elif defined(LPC43XX)
 #	include <libopencm3/lpc43xx/nvic.h>
 
+#elif defined(LM3S)
+#	include <libopencm3/lm3s/nvic.h>
+
 #else
-#	warning"no chipset defined; user interrupts are disabled"
+#	warning"no interrupts defined for chipset; NVIC_IRQ_COUNT = 0"
 
 #define NVIC_IRQ_COUNT 0
 

lib/dispatch/vector_nvic.c

@@ -11,8 +11,11 @@
 #elif defined(LPC43XX)
 #	include "../lpc43xx/vector_nvic.c"
 
+#elif defined(LM3S)
+#	include "../lm3s/vector_nvic.c"
+
 #else
-#	warning"no chipset defined; user interrupts are disabled"
+#	warning"no interrupts defined for chipset; not allocating space in the vector table"
 
 #define IRQ_HANDLERS