Subtree merged in deps/jansson

deps/jansson/cmake/CheckFunctionKeywords.cmake

@@ -0,0 +1,15 @@
+include(CheckCSourceCompiles)
+
+macro(check_function_keywords _wordlist)
+  set(${_result} "")
+  foreach(flag ${_wordlist})
+    string(REGEX REPLACE "[-+/ ()]" "_" flagname "${flag}")
+    string(TOUPPER "${flagname}" flagname)
+    set(have_flag "HAVE_${flagname}")
+    check_c_source_compiles("${flag} void func(); void func() { } int main() { func(); return 0; }" ${have_flag})
+    if(${have_flag} AND NOT ${_result})
+      set(${_result} "${flag}")
+#      break()
+    endif(${have_flag} AND NOT ${_result})
+  endforeach(flag)
+endmacro(check_function_keywords)