make gdb test automation even awesomer

baremetal/arch/aarch64/regs.S

@@ -3,7 +3,6 @@
  * - read x30 */
 .global main
 main:
-    /* test-gdb-before-x29 */
     mov x0, #1
     /* test-gdb-x0 */
     mov x1, #2

baremetal/arch/aarch64/regs.py

@@ -1,7 +1,11 @@
 def test(self):
     self.sendline('tbreak main')
     self.sendline('continue')
+    self.continue_to('x0')
+    self.sendline('set $x0 = 3')
     self.continue_to('x1')
+    assert self.get_int('$x0') == 3
+    assert self.get_int('$x1') == 2
     self.sendline('set $x30 = 3')
     self.continue_to('x29')
     assert self.get_int('$x29') == 1

baremetal/arch/arm/regs.S

@@ -0,0 +1,8 @@
+/* See the aarch64 version. */
+.global main
+main:
+    mov r0, #1
+    /* test-gdb-r0 */
+    mov r1, #2
+    /* test-gdb-r1 */
+    bx lr

baremetal/arch/arm/regs.py

@@ -0,0 +1,8 @@
+def test(self):
+    self.sendline('tbreak main')
+    self.sendline('continue')
+    self.continue_to('r0')
+    self.sendline('set $r0 = 3')
+    self.continue_to('r1')
+    assert self.get_int('$r0') == 3
+    assert self.get_int('$r1') == 2

baremetal/lib/common.c

@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <stdlib.h>
 #include <sys/stat.h>