Support %ebp register in 'struct bregs'.

Save/restore %ebp on irq entry.
Support saving and restoring %ebp on call16.
Enable display of %ebp in register dumps.
diff --git a/src/asm-offsets.c b/src/asm-offsets.c
index c3c3bc6..ea49296 100644
--- a/src/asm-offsets.c
+++ b/src/asm-offsets.c
@@ -16,6 +16,7 @@
     OFFSET(BREGS_ebx, bregs, ebx);
     OFFSET(BREGS_ecx, bregs, ecx);
     OFFSET(BREGS_edx, bregs, edx);
+    OFFSET(BREGS_ebp, bregs, ebp);
     OFFSET(BREGS_esi, bregs, esi);
     OFFSET(BREGS_edi, bregs, edi);
     OFFSET(BREGS_flags, bregs, flags);