Merge pull request #742 from AlisdairM/fix_stdarg_header_typo_in_index

[support.runtime] Fix name of stdarg.h in index

Author: jwakely

source/support.tex

@@ -3365,7 +3365,7 @@
 \indexlibrary{\idxcode{va_start}}%
 \tcode{va_start()}
 macro in header
-\indexlibrary{\idxhdr{staarg.h}}%
+\indexlibrary{\idxhdr{stdarg.h}}%
 \tcode{<stdarg.h>}
 are different in this International Standard.
 The parameter