sys/targets: use kernel.full instead of kernel.debug

The latter contains only debug symbols and is meant to be used with the
kernel executable.  That is, the kernel executable contains a
.gnu_debuglink pointer to kernel.debug.  kernel.full contains
everything, including a copy of the kernel's text section, which we want
when enumerating __sanitizer_cov_trace_pc() calls for a coverage report.
diff --git a/sys/targets/targets.go b/sys/targets/targets.go
index 37737f1..eaf6cc8 100644
--- a/sys/targets/targets.go
+++ b/sys/targets/targets.go
@@ -302,7 +302,7 @@
 		SyscallPrefix:          "SYS_",
 		ExecutorUsesShmem:      true,
 		ExecutorUsesForkServer: true,
-		KernelObject:           "kernel.debug",
+		KernelObject:           "kernel.full",
 		CPP:                    "g++",
 	},
 	"netbsd": {