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);
 
@@ -455,7 +455,7 @@ vm_setup_memory(struct vmctx *ctx, size_t memsize, enum vm_mmap_style vms)
 	 * and the adjoining guard regions.
 	 */
 	len = VM_MMAP_GUARD_SIZE + objsize + VM_MMAP_GUARD_SIZE;
-	ptr = mmap(NULL, len, PROT_NONE | PROT_MAX(PROT_RW),
+	ptr = mmap(NULL, len, PROT_NONE | PROT_MAX(PROT_RW | PROT_CAP),
 	    MAP_GUARD | MAP_ALIGNED_SUPER, -1, 0);
 	if (ptr == MAP_FAILED)
 		return (-1);