fix: remove Apple assembly files before building BoringSSL on Linux

BoringSSL's CMake configuration was incorrectly trying to compile
Apple-specific assembly files (e.g., aes-gcm-avx2-x86_64-apple.S)
on Linux runners, causing build failures.

Root cause: BoringSSL ships with pre-generated assembly files for
all platforms (apple, linux, win) and CMake should filter them based
on the target platform. However, something in the GitHub Actions
environment was confusing the platform detection.

Workaround: Explicitly remove Apple-specific assembly files before
running CMake on Linux. This ensures only Linux-compatible assembly
files are present during the build.

Changes:
- Add find command to delete *-apple.S files on Linux
- Unset APPLE environment variable that might confuse CMake
- This is a temporary workaround until root cause is identified

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: arman-bd

scripts/linux/setup_vendors.sh

@@ -72,6 +72,12 @@ if [ ! -f "build/libssl.a" ]; then
     unset CMAKE_OSX_ARCHITECTURES
     unset CMAKE_OSX_DEPLOYMENT_TARGET
     unset CMAKE_OSX_SYSROOT
+    unset APPLE
+
+    # Workaround: Remove Apple-specific assembly files that shouldn't be built on Linux
+    # BoringSSL's CMake sometimes incorrectly tries to build these on Linux
+    echo "Removing Apple-specific assembly files..."
+    find ../gen/bcm -name "*-apple.S" -delete || true
 
     cmake -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_POSITION_INDEPENDENT_CODE=ON \