Add double batched FFT library package (spack#36086)

* Add double batched FFT library package
* Fix style
* Add error when unsupported compiler is uesd

---------

Signed-off-by: Carsten Uphoff <carsten.uphoff@intel.com>

var/spack/repos/builtin/packages/double-batched-fft-library/package.py

@@ -0,0 +1,51 @@
+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+import os
+
+from spack.package import *
+
+
+class DoubleBatchedFftLibrary(CMakePackage):
+    """A library for computing the Discrete Fourier Transform;
+    targeting Graphics Processing Units; supporting OpenCL,
+    Level Zero, and SYCL; with double-batching."""
+
+    homepage = "https://github.com/intel/double-batched-fft-library"
+    url = "https://github.com/intel/double-batched-fft-library/archive/refs/tags/v0.3.6.tar.gz"
+    git = "https://github.com/intel/double-batched-fft-library.git"
+
+    maintainers = ["uphoffc"]
+
+    version("main", branch="main")
+    version("develop", branch="develop")
+    version("0.3.6", sha256="ff163251d77d3c686563141e871c702bf4997c0302d53616add55d6cf9b02d28")
+
+    variant("shared", default=True, description="Shared library")
+    variant("sycl", default=True, description="Build bbfft-sycl")
+    variant("level-zero", default=True, when="~sycl", description="Build bbfft-level-zero")
+    variant("opencl", default=True, when="~sycl", description="Build bbfft-opencl")
+
+    depends_on("cmake@3.23.0:", type="build")
+    depends_on("oneapi-level-zero", when="+sycl")
+    depends_on("oneapi-level-zero", when="+level-zero")
+    depends_on("opencl", when="+opencl")
+
+    def cmake_args(self):
+        cxx_compiler = os.path.basename(self.compiler.cxx)
+        if self.spec.satisfies("+sycl") and cxx_compiler not in ["icpx", "dpcpp"]:
+            raise InstallError(
+                "The Double-Batched FFT Library requires the oneapi DPC++/C++ Compiler"
+            )
+
+        return [
+            self.define_from_variant("BUILD_SHARED_LIBS", "shared"),
+            self.define_from_variant("BUILD_SYCL", "sycl"),
+            self.define_from_variant("BUILD_LEVEL_ZERO", "level-zero"),
+            self.define_from_variant("BUILD_OPENCL", "opencl"),
+            self.define("BUILD_BENCHMARK", False),
+            self.define("BUILD_EXAMPLE", False),
+            self.define("BUILD_TESTING", False),
+        ]