Use same tcl initialization as in OpenROAD

In https://github.com/The-OpenROAD-Project/OpenROAD/pull/10041
we have a new way to initializa the tcl subsystem which
will allow to be entirely independent of separate files
once we can switch to Tcl9.

Signed-off-by: Henner Zeller <h.zeller@acm.org>

BUILD

@@ -272,7 +272,6 @@ cc_binary(
         "app/Main.cc",
         ":StaApp",
         ":StaTclInitVar",
-        "//bazel:runfiles",
     ],
     copts = [
         "-Wno-error",
@@ -297,6 +296,7 @@ cc_binary(
     visibility = ["//visibility:public"],
     deps = [
         ":opensta_lib",
+        "//bazel:tcl_library_init",
         "@rules_cc//cc/runfiles",
         "@tcl_lang//:tcl",
     ],

app/Main.cc

@@ -30,6 +30,11 @@
 #include <filesystem>
 #include <string_view>
 #include <tcl.h>
+
+#ifdef BAZEL_CURRENT_REPOSITORY
+  #include "bazel/tcl_library_init.h"
+#endif
+
 #if TCL_READLINE
   #include <tclreadline.h>
 #endif
@@ -109,6 +114,12 @@ staTclAppInit(int argc,
               std::string_view init_filename,
               Tcl_Interp *interp)
 {
+#ifdef BAZEL_CURRENT_REPOSITORY
+    if (in_bazel::SetupTclEnvironment(interp) == TCL_ERROR) {
+      return TCL_ERROR;
+    }
+#endif
+
   // source init.tcl
   if (Tcl_Init(interp) == TCL_ERROR)
     return TCL_ERROR;