fbt: 'target' field for apps; lib debugging support (#1995)

* fbt: added 'target' field to application manifest
* fbt: earlier pagination setup for gdb
* fbt: added LIB_DEBUG flag
* fbt: sdk: added SDK_MAP_FILE_SUBST

scripts/fbt_tools/fbt_sdk.py

@@ -14,6 +14,7 @@ import json
 
 from fbt.sdk.collector import SdkCollector
 from fbt.sdk.cache import SdkCache
+from fbt.util import path_as_posix
 
 
 def ProcessSdkDepends(env, filename):
@@ -52,6 +53,8 @@ def prebuild_sdk_create_origin_file(target, source, env):
 
 
 class SdkMeta:
+    MAP_FILE_SUBST = "SDK_MAP_FILE_SUBST"
+
     def __init__(self, env, tree_builder: "SdkTreeBuilder"):
         self.env = env
         self.treebuilder = tree_builder
@@ -67,6 +70,7 @@ class SdkMeta:
             "linker_libs": self.env.subst("${LIBS}"),
             "app_ep_subst": self.env.subst("${APP_ENTRY}"),
             "sdk_path_subst": self.env.subst("${SDK_DIR_SUBST}"),
+            "map_file_subst": self.MAP_FILE_SUBST,
             "hardware": self.env.subst("${TARGET_HW}"),
         }
         with open(json_manifest_path, "wt") as f:
@@ -75,9 +79,9 @@ class SdkMeta:
     def _wrap_scons_vars(self, vars: str):
         expanded_vars = self.env.subst(
             vars,
-            target=Entry("dummy"),
+            target=Entry(self.MAP_FILE_SUBST),
         )
-        return expanded_vars.replace("\\", "/")
+        return path_as_posix(expanded_vars)
 
 
 class SdkTreeBuilder:
@@ -142,13 +146,15 @@ class SdkTreeBuilder:
         meta.save_to(self.target[0].path)
 
     def build_sdk_file_path(self, orig_path: str) -> str:
-        return posixpath.normpath(
-            posixpath.join(
-                self.SDK_DIR_SUBST,
-                self.target_sdk_dir_name,
-                orig_path,
+        return path_as_posix(
+            posixpath.normpath(
+                posixpath.join(
+                    self.SDK_DIR_SUBST,
+                    self.target_sdk_dir_name,
+                    orig_path,
+                )
             )
-        ).replace("\\", "/")
+        )
 
     def emitter(self, target, source, env):
         target_folder = target[0]