Fix build problems in commit aa65de042f.

The previous way didn't work for vpath builds, and make distprep was
busted too.

Reported off-list by Andres Freund.

src/backend/Makefile

@@ -200,7 +200,7 @@ distprep:
 	$(MAKE) -C bootstrap	bootparse.c bootscanner.c
 	$(MAKE) -C catalog	schemapg.h postgres.bki postgres.description postgres.shdescription
 	$(MAKE) -C replication	repl_gram.c repl_scanner.c
-	$(MAKE) -C storage	lwlocknames.h
+	$(MAKE) -C storage/lmgr	lwlocknames.h
 	$(MAKE) -C utils	fmgrtab.c fmgroids.h errcodes.h
 	$(MAKE) -C utils/misc	guc-file.c
 	$(MAKE) -C utils/sort	qsort_tuple.c

src/backend/storage/lmgr/Makefile

@@ -12,7 +12,8 @@ subdir = src/backend/storage/lmgr
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = lmgr.o lock.o proc.o deadlock.o lwlock.o spin.o s_lock.o predicate.o
+OBJS = lmgr.o lock.o proc.o deadlock.o lwlock.o lwlocknames.o spin.o \
+	s_lock.o predicate.o
 
 include $(top_srcdir)/src/backend/common.mk
 

src/backend/storage/lmgr/generate-lwlocknames.pl

@@ -23,7 +23,7 @@ print H $autogen;
 print H "/* there is deliberately not an #ifndef LWLOCKNAMES_H here */\n\n";
 print C $autogen, "\n";
 
-print C "static char *MainLWLockNames[] = {";
+print C "char *MainLWLockNames[] = {";
 
 while (<$lwlocknames>)
 {

src/backend/storage/lmgr/lwlock.c

@@ -95,9 +95,6 @@
 #include "utils/hsearch.h"
 #endif
 
-/* Constants for lwlock names */
-#include "lwlocknames.c"
-
 
 /* We use the ShmemLock spinlock to protect LWLockAssign */
 extern slock_t *ShmemLock;

src/include/storage/lwlock.h

@@ -90,9 +90,10 @@ typedef union LWLockPadded
 	char		pad[LWLOCK_PADDED_SIZE];
 } LWLockPadded;
 extern PGDLLIMPORT LWLockPadded *MainLWLockArray;
+extern char *MainLWLockNames[];
 
 /* Names for fixed lwlocks */
-#include "lwlocknames.h"
+#include "storage/lwlocknames.h"
 
 /*
  * It's a bit odd to declare NUM_BUFFER_PARTITIONS and NUM_LOCK_PARTITIONS