Fixes for GCC 15.

--- sqlite-2.8.17/Makefile.in	2005-04-23 23:43:23.000000000 +0100
+++ sqlite-2.8.17/Makefile.in	2025-07-04 04:03:13.976989637 +0100
@@ -271,7 +271,7 @@
 	echo '#include <stdio.h>' >temp.c
 	echo 'int main(){printf(' >>temp.c
 	echo '"#define SQLITE_PTR_SZ %d",sizeof(char*));' >>temp.c
-	echo 'exit(0);}' >>temp.c
+	echo 'return 0;}' >>temp.c
 	$(BCC) -o temp temp.c
 	./temp >config.h
 	echo >>config.h
--- sqlite-2.8.17/main.mk	2005-04-23 23:43:23.000000000 +0100
+++ sqlite-2.8.17/main.mk	2025-07-04 04:02:11.633041105 +0100
@@ -242,7 +242,7 @@
 	echo '#include <stdio.h>' >temp.c
 	echo 'int main(){printf(' >>temp.c
 	echo '"#define SQLITE_PTR_SZ %d",sizeof(char*));' >>temp.c
-	echo 'exit(0);}' >>temp.c
+	echo 'return 0;}' >>temp.c
 	$(BCC) -o temp temp.c
 	./temp >config.h
 	echo >>config.h
--- sqlite-2.8.17/tool/lemon.c	2005-04-23 23:43:22.000000000 +0100
+++ sqlite-2.8.17/tool/lemon.c	2025-07-04 04:02:34.716611918 +0100
@@ -11,6 +11,7 @@
 #include <string.h>
 #include <ctype.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #ifndef __WIN32__
 #   if defined(_WIN32) || defined(WIN32)