bpo-30636: Add PYTHONCOERCECLOCALE to the help of the command line (GH-2125)

diff --git a/Modules/main.c b/Modules/main.c
index 438cb2c..6a7e1d3 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -106,6 +106,9 @@
 "PYTHONMALLOC: set the Python memory allocators and/or install debug hooks\n"
 "   on Python memory allocators. Use PYTHONMALLOC=debug to install debug\n"
 "   hooks.\n";
+static const char usage_7[] =
+"PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale\n"
+"coercion behavior\n";
 
 static int
 usage(int exitcode, const wchar_t* program)
@@ -122,6 +125,7 @@
         fprintf(f, usage_4, (wint_t)DELIM);
         fprintf(f, usage_5, (wint_t)DELIM, PYTHONHOMEHELP);
         fputs(usage_6, f);
+        fputs(usage_7, f);
     }
     return exitcode;
 }