check if cppformat is the master project or just used as dependency

Based on that information less intrusive option defaults are choosen.
Additionally, packaging support is omitted.

test/add_subdirectory-test/CMakeLists.txt

@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 2.8.12)
+
+project(cppformat-test)
+
+add_subdirectory(../.. cppformat)
+
+add_executable(library-test "main.cpp")
+target_link_libraries(library-test cppformat)
+
+if (TARGET cppformat-header-only)
+  add_executable(header-only-test "main.cpp")
+  target_link_libraries(header-only-test cppformat-header-only)
+endif ()

test/add_subdirectory-test/main.cpp

@@ -0,0 +1,8 @@
+#include "cppformat/format.h"
+
+int main(int argc, char** argv)
+{
+  for(int i = 0; i < argc; ++i)
+    fmt::print("{}: {}\n", i, argv[i]);
+  return 0;
+}