ensure NDEBUG is set consistently

otherwise grpcio ends up with missing symbols at runtime, because
```
class DomainStorage : public DualRefCounted<DomainStorage>, public channelz::DataSource
```
ends up having a different class layout, due to inheriting from DualRefCounted,
which changes size depending on NDEBUG being present or not, see
https://github.com/grpc/grpc/blob/v1.78.0-pre1/src/core/util/dual_ref_counted.h

Author: h-vetinari

recipe/build-cpp.sh

@@ -71,6 +71,11 @@ pushd build-cpp
 echo CC="${CC}"
 echo CFLAGS="${CFLAGS}"
 
+# our compilers set `-DNDEBUG` in CPPFLAGS, but grpc does not seem to respect
+# this consistently; add it to CXXFLAGS as well to avoid any doubt, see
+# https://github.com/abseil/abseil-cpp/issues/1624#issuecomment-1968073823
+CXXFLAGS="${CXXFLAGS} -DNDEBUG"
+
 # point to right protoc
 if [[ "$CONDA_BUILD_CROSS_COMPILATION" == 1 ]]; then
     export CMAKE_ARGS="${CMAKE_ARGS} -DProtobuf_PROTOC_EXECUTABLE=$BUILD_PREFIX/bin/protoc"

recipe/build-grpcio.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+set -ex
 
 export GRPC_BUILD_WITH_BORING_SSL_ASM=""
 export GRPC_PYTHON_BUILD_SYSTEM_ABSL="True"
@@ -25,4 +26,9 @@ fi
 ln -sf "$(which $CC)" "$SRC_DIR/cc"
 export PATH="$SRC_DIR:$PATH"
 
+# our compilers set `-DNDEBUG` in CPPFLAGS, but grpc does not seem to respect
+# this consistently; add it to CXXFLAGS as well to avoid any doubt, see
+# https://github.com/abseil/abseil-cpp/issues/1624#issuecomment-1968073823
+CXXFLAGS="${CXXFLAGS} -DNDEBUG"
+
 $PYTHON -m pip install . --no-deps --ignore-installed --no-cache-dir -v