pio: update ldpath as soon as possible

trying to fix #2343
*** [.pio\build\$PIOENV\firmware.bin] TypeError
`expected str, bytes or os.PathLike object, not Dir' trying to evaluate `${__get_flash_size(__env__)}'

as it turns out, PIO platform internals (sometimes) did not use the correct ldscript path

code/scripts/espurna_utils/ldscripts.py

@@ -1,23 +1,22 @@
 import os
 
 def ldscripts_inject_libpath(env):
-
     platform = env.PioPlatform()
     framework_dir = platform.get_package_dir("framework-arduinoespressif8266")
 
-    # espressif8266@1.5.0 did not append this directory into the LIBPATH
-    libpath_sdk = os.path.join(framework_dir, "tools", "sdk", "ld")
-    env.Append(LIBPATH=[libpath_sdk])
-
     libpath_base = os.path.join("$PROJECT_DIR", "..", "dist", "ld")
-    env.Append(LIBPATH=[os.path.join(libpath_base, "pre_2.5.0")])
 
-    # local.eagle.app.v6.common.ld exists only with Core >2.5.0
-    def check_local_ld(target, source, env):
+    # we depend on different ldscript formats for old Core version
+    # TODO: 1.5.0 needs to be removed next release
+    # TODO: ldscript can be kept in the root of the repo
+    #       (as this was done originally, during 2.3.0...2.4.2 times)
+
+    if platform.version == "1.5.0":
+        libpath_sdk = os.path.join(framework_dir, "tools", "sdk", "ld")
+        env.Append(LIBPATH=[libpath_sdk])
+        env.Prepend(LIBPATH=[os.path.join(libpath_base, "pre_2.5.0")])
+    else:
         local_ld = env.subst(
             os.path.join("$BUILD_DIR", "ld", "local.eagle.app.v6.common.ld")
         )
-        if os.path.exists(local_ld):
-            env.Prepend(LIBPATH=[os.path.join(libpath_base, "latest")])
-
-    env.AddPreAction(os.path.join("$BUILD_DIR", "firmware.elf"), check_local_ld)
+        env.Prepend(LIBPATH=[os.path.join(libpath_base, "latest")])