adding global variable simdjson_development_checks_enabled

doc/basics.md

@@ -379,6 +379,8 @@ tracking explicitly potential programming mistakes. Thus you should not relying
 size (`sizeof`) of our data structures to be constant: they may change depending on the
 compiler settings.
 
+When `SIMDJSON_DEVELOPMENT_CHECKS` is set at compile time, the global variable `simdjson_development_checks_enabled` is defined as true. It is false otherwise.
+
 Once your code has been tested, you can then run it in
 Release mode: under Visual Studio, it means having the `_DEBUG` macro undefined, and, for other
 compilers, it means setting `__OPTIMIZE__` to a positive integer. You can also forcefully

include/simdjson/common_defs.h

@@ -297,6 +297,15 @@ namespace std {
 #endif // _MSC_VER
 #endif // SIMDJSON_DEVELOPMENT_CHECKS
 
+
+// Prevent ODR violations for the simdjson_development_checks_enabled variable.
+#if SIMDJSON_DEVELOPMENT_CHECKS
+extern const bool simdjson_development_checks_enabled = true;
+#else
+extern const bool simdjson_development_checks_enabled = false;
+#endif // SIMDJSON_DEVELOPMENT_CHECKS
+
+
 // The SIMDJSON_CHECK_EOF macro is a feature flag for the "don't require padding"
 // feature.