Improve LTO variable handling in build action

Refactor LTO handling in build scripts for better clarity and maintainability.

.github/actions/build/action.yml

@@ -19,25 +19,36 @@ runs:
      set -x
      cd "$CONFIG"
      echo "Building the kernel..."
+
+     # 1. Initialize variables as empty (clears them out for "default")
+     BAZEL_LTO=""
+     SCRIPT_LTO=""
+
+     # 2. Only populate if explicit modifications are requested
+     if [[ "$LTO" == "thin" || "$LTO" == "full" ]]; then
+       BAZEL_LTO="--lto=$LTO"
+       SCRIPT_LTO="LTO=$LTO"
+     fi
+
      if [[ $BRANCH == SM-A055* || $BRANCH == SM-X926B* ]]; then
       chmod +x build_kernel.sh
-      LTO="$LTO" ./build_kernel.sh || true
+      env $SCRIPT_LTO ./build_kernel.sh || true
      elif [[ $BRANCH == SM-S926* ]]; then
        #tools/bazel run --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I //projects/s5e9945:s5e9945_user_dist
-       tools/bazel build --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I --lto="$LTO" //projects/s5e9945:s5e9945_user
+       tools/bazel build --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I $BAZEL_LTO //projects/s5e9945:s5e9945_user
       elif [[ $BRANCH == SM-A556* ]]; then
        #tools/bazel run --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I //projects/s5e8845:s5e8845_user_dist
-       tools/bazel build --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I --lto="$LTO" //projects/s5e8845:s5e8845_user
+       tools/bazel build --nocheck_bzl_visibility --config=stamp --sandbox_debug --verbose_failures --debug_make_verbosity=I $BAZEL_LTO //projects/s5e8845:s5e8845_user
      elif [[ $BRANCH == SM-S938B* ]]; then
       sed -i '/drivers\/net\/usb\/smsc75xx\.ko/d;/drivers\/net\/usb\/smsc95xx\.ko/d' kernel_platform/common/modules.bzl
       chmod +x build_kernel_GKI.sh
-      LTO="$LTO" ./build_kernel_GKI.sh || true
+      env $SCRIPT_LTO ./build_kernel_GKI.sh || true
      elif [[ $KERNEL_VER == 6.* ]]; then
       chmod +x build_kernel_GKI.sh
-      LTO="$LTO" ./build_kernel_GKI.sh || true
+      env $SCRIPT_LTO ./build_kernel_GKI.sh || true
      elif [[ -d kernel_platform ]]; then
       cd kernel_platform
-      tools/bazel build --lto="$LTO" //common:kernel_aarch64
+      tools/bazel build $BAZEL_LTO //common:kernel_aarch64
      fi
       
   - name: start make build
@@ -49,12 +60,12 @@ runs:
      cd "$CONFIG"
      if [[ -f build_kernel_GKI.sh ]]; then
       chmod +x build_kernel_GKI.sh
-      LTO="$LTO" ./build_kernel_GKI.sh || true
+      env $SCRIPT_LTO ./build_kernel_GKI.sh || true
      elif [[ -f build_kernel.sh ]]; then
       sudo apt update
       sudo apt-get install -y libyaml-dev
       chmod +x build_kernel.sh
-      LTO="$LTO" ./build_kernel.sh || true
+      env $SCRIPT_LTO ./build_kernel.sh || true
      fi
      
      #if [[ $BRANCH == SM-S928B* || "$BRANCH" == "SM-S938B-Oneui7" || "$BRANCH" == "SM-S931B-Oneui8" || "$BRANCH" == "SM-F741B-Oneui8" || "$BRANCH" == "SM-X710-Oneui6.1.1" ]]; then