Minor CANNOT_DUMP cleanups

Mostly, this avoids munging executables when CANNOT_DUMP = yes,
as the munging is needed only for unexec.
* configure.ac (PAXCTL_dumped, PAXCTL_notdumped) [CANNOT_DUMP]:
Leave these empty.
(LD_SWITCH_SYSTEM_TEMACS) [CANNOT_DUMP]:
Do not append -no-pie or -nopie.
* src/alloc.c (my_heap_start) [CANNOT_DUMP]: Omit; not used.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 7b2140501ec..286358662b9 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -104,7 +104,7 @@ static bool valgrind_p;
 #include "w32heap.h"    /* for sbrk */
 #endif
 
-#ifdef GNU_LINUX
+#if defined GNU_LINUX && !defined CANNOT_DUMP
 /* The address where the heap starts.  */
 void *
 my_heap_start (void)