Allow linking against system libraries for almost everything (#1790)

extern/CMakeProject-cppformat.cmake

@@ -1,15 +1,14 @@
-if (NOT IS_DIRECTORY "${SM_EXTERN_DIR}/cppformat")
-  message(ERROR "Submodule for cppformat missing. Run git submodule init && git submodule update first.")
+if(NOT IS_DIRECTORY "${SM_EXTERN_DIR}/cppformat")
+  message(
+    ERROR
+    "Submodule for cppformat missing. Run git submodule init && git submodule update first."
+    )
   return()
 endif()
 
-list(APPEND CPPFORMAT_SRC
-  "cppformat/fmt/format.cc"
-)
+list(APPEND CPPFORMAT_SRC "cppformat/fmt/format.cc")
 
-list(APPEND CPPFORMAT_HPP
-  "cppformat/fmt/format.h"
-)
+list(APPEND CPPFORMAT_HPP "cppformat/fmt/format.h")
 
 source_group("" FILES ${CPPFORMAT_SRC} ${CPPFORMAT_HPP})
 
@@ -21,19 +20,19 @@ disable_project_warnings("cppformat")
 
 target_include_directories("cppformat" PUBLIC "cppformat")
 
-if (MSVC)
+if(MSVC)
   sm_add_compile_definition("cppformat" _CRT_SECURE_NO_WARNINGS)
 elseif(APPLE)
-  set_target_properties("cppformat" PROPERTIES
-    XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "${SM_CPP_STANDARD}"
-    XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++"
-  )
+  set_target_properties("cppformat"
+                        PROPERTIES XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD
+                                   "${SM_CPP_STANDARD}"
+                                   XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY
+                                   "libc++")
   sm_add_compile_flag("cppformat" "-std=${SM_CPP_STANDARD}")
   sm_add_compile_flag("cppformat" "-stdlib=libc++")
 else() # Unix
   sm_add_compile_flag("cppformat" "-std=${SM_CPP_STANDARD}")
-  if (CMAKE_CXX_COMPILER MATCHES "clang")
+  if(CMAKE_CXX_COMPILER MATCHES "clang")
     sm_add_compile_flag("cppformat" "-stdlib=libc++")
   endif()
 endif()
-