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

--- sqlite-src-3470200/tool/buildtclext.tcl.~1~	2024-12-07 15:57:39.000000000 -0500
+++ sqlite-src-3470200/tool/buildtclext.tcl	2025-01-05 02:22:29.634735763 -0500
@@ -256,7 +256,7 @@
 
   # Generate and execute the command with which to do the compilation.
   #
-  set cmd "$CMD tclsqlite3.c -o $OUT $LIBS"
+  set cmd "$CMD tclsqlite3.c -fPIC -o $OUT $LIBS"
   puts $cmd
   file delete -force $OUT
   catch {exec {*}$cmd} errmsg