CFLAGS aren't getting set in buildtclext.tcl. Force -fPIC usage.

--- sqlite-src-3530100/tool/buildtclext.tcl.orig	2026-05-05 12:49:11.000000000 +0200
+++ sqlite-src-3530100/tool/buildtclext.tcl	2026-05-06 19:26:07.644565951 +0200
@@ -317,7 +317,7 @@
 
   # Generate and execute the command with which to do the compilation.
   #
-  set cmd "$CMD -DUSE_TCL_STUBS tclsqlite3.c -o $OUT [join $LIBS { }]"
+  set cmd "$CMD -DUSE_TCL_STUBS tclsqlite3.c -fPIC -o $OUT [join $LIBS { }]"
   puts $cmd
   file delete -force $OUT
   catch {exec {*}$cmd} errmsg