Move the old cmakefiles to create the new ones

old_cmake/benchmark.txt

@@ -1,5 +1,18 @@
 project(sfizz)
 
+include(FetchContent)
+FetchContent_Declare(
+  benchmark
+  GIT_REPOSITORY https://github.com/google/benchmark.git
+  GIT_TAG        v1.5.0
+)
+
+FetchContent_GetProperties(benchmark)
+if(NOT benchmark_POPULATED)
+  FetchContent_Populate(benchmark)
+  add_subdirectory(${benchmark_SOURCE_DIR} ${benchmark_BINARY_DIR})
+endif()
+
 # Check SIMD
 include(CheckIncludeFiles)
 CHECK_INCLUDE_FILES(x86intrin.h HAVE_X86INTRIN_H)