libvmmapi: Map the guest physical address space with PROT_CAP

This lets the gdb stub see capability tag bits; otherwise, they're cleared on
load and the debugger sees all capabilities as invalid.

Note that this enables the writing of capabilities to the GPA space as well.

lib/libvmmapi/vmmapi.c

@@ -415,7 +415,7 @@ setup_memory_segment(struct vmctx *ctx, vm_paddr_t gpa, size_t len, char *base)
 		flags |= MAP_NOCORE;
 
 	/* mmap into the process address space on the host */
-	ptr = mmap(base + gpa, len, PROT_RW, flags, ctx->fd, gpa);
+	ptr = mmap(base + gpa, len, PROT_RW | PROT_CAP, flags, ctx->fd, gpa);
 	if (ptr == MAP_FAILED)
 		return (-1);