dlibs: make expand_for_kernel work if invoked more than once

The expand_for_kernel macro had an extremely embarrassing bug:
because it always defined a macro with the same name, and because M4
defines all macros before doing any expansions, calling
define_for_kernel twice always duplicated the expansion of the first
in the second invocation, no matter what the second invocation was.

This is unlikely to be what anyone wants.

Fixed by introducing a name (required to be unique, though we do not
validate this) and using that name to inflect the name of the macro
we define in expand_for_kernel.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

libdtrace/d-kern.m4

@@ -1,6 +1,6 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2020, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  *
@@ -51,9 +51,9 @@ m4_define([[__define_for_kernel]], [[ m4_dnl
 m4_define([[define_for_kernel]], [[m4_divert(-1) __define_for_kernel($@) m4_divert(0)]])m4_dnl
 
 /*
- * expand_for_kernel([[(kver, value), (kver, value), ...]], [[default]])
+ * expand_for_kernel(name, [[(kver, value), (kver, value), ...]], [[default]])
  *
  * As define_for_kernel, but simply substitutes the result into the output
- * rather than defining a macro.
+ * rather than defining a macro.  Every NAME should be unique.
  */
-m4_define([[expand_for_kernel]], [[define_for_kernel(__foo, $@)__foo]])m4_dnl
+m4_define([[expand_for_kernel]], [[define_for_kernel(__expand_for_kernel_$1, m4_shift($@))__expand_for_kernel_$1]])m4_dnl

libdtrace/procfs.d.in

@@ -113,7 +113,7 @@ define_for_kernel([[__pidtype_sid]], [[ m4_dnl
 
 inline	int PIDTYPE_PID = 0;
 #pragma D binding "1.0" PIDTYPE_PID
-expand_for_kernel([[ (m4_kver(4,19,0), [[ m4_dnl
+expand_for_kernel([[pidtype_tgid]], [[ (m4_kver(4,19,0), [[ m4_dnl
 inline	int PIDTYPE_TGID = 1;
 #pragma D binding "1.0" PIDTYPE_TGID]])]])
 inline	int PIDTYPE_PGID = __pidtype_pgid;