Enable exceptions explicitly on Android in CI

After c52806157c97105da7fdc2b021d0a0fcd5186bf3, BoringSSL requires
a C++ runtime in libssl, but the NDK doesn't enable C++ exceptions
by default.

Author: nox

.github/workflows/ci.yml

@@ -233,6 +233,9 @@ jobs:
     - name: Set Android Linker path
       if: endsWith(matrix.thing, '-android')
       run: echo "CARGO_TARGET_$(echo ${{ matrix.target }} | tr \\-a-z _A-Z)_LINKER=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/$(echo ${{ matrix.target }} | sed s/armv7/armv7a/)21-clang++" >> "$GITHUB_ENV"
+    - name: Enable exceptions explicitly on Android
+      if: endsWith(matrix.thing, '-android')
+      run: echo CXXFLAGS=-fexceptions >> "$GITHUB_ENV"
     - name: Build tests
       # We `build` because we want the linker to verify we are cross-compiling correctly for check-only targets.
       run: cargo build --target ${{ matrix.target }} --tests ${{ matrix.extra_test_args }}