fix adaptivecpp installs scripts

scripts/install_opensycl.sh

@@ -1,10 +1,44 @@
 #!/usr/bin/bash
 
-LLVM_VERSION=14
-ACCELERATED_CPU=ON
-OPENCL_BACKEND=ON
-CUDA_BACKEND=ON
-BUILD_TYPE=Release
+if [[ -z "${LLVM_VERSION}" ]]; then
+  LLVM_VERSION="14"
+else
+  LLVM_VERSION="${LLVM_VERSION}"
+  echo "set LLVM_VERSION from env"
+fi
+
+if [[ -z "${ACCELERATED_CPU}" ]]; then
+  ACCELERATED_CPU="ON"
+else
+  ACCELERATED_CPU="${ACCELERATED_CPU}"
+  echo "set ACCELERATED_CPU from env"
+fi
+
+if [[ -z "${OPENCL_BACKEND}" ]]; then
+  OPENCL_BACKEND="ON"
+else
+  OPENCL_BACKEND="${OPENCL_BACKEND}"
+  echo "set OPENCL_BACKEND from env"
+fi
+
+if [[ -z "${CUDA_BACKEND}" ]]; then
+  CUDA_BACKEND="ON"
+else
+  CUDA_BACKEND="${CUDA_BACKEND}"
+  echo "set CUDA_BACKEND from env"
+fi
+
+if [[ -z "${BUILD_TYPE}" ]]; then
+  BUILD_TYPE="Release"
+else
+  BUILD_TYPE="${BUILD_TYPE}"
+  echo "set BUILD_TYPE from env"
+fi
+
+echo "using LLVM_VERSION=${LLVM_VERSION}"
+echo "using ACCELERATED_CPU=${ACCELERATED_CPU}"
+echo "using OPENCL_BACKEND=${OPENCL_BACKEND}"
+echo "using CUDA_BACKEND=${CUDA_BACKEND}"
 
 DIR=OpenSYCL
 GIT_REPOSITORY=https://github.com/OpenSYCL/OpenSYCL