dg-require-supportA few of the dg-require directives take arguments.
     
dg-require-iconv codesetdg-require-profiling profoptdg-require-visibility visvisibility attribute. 
If vis is "", support for visibility("hidden") is
checked, for visibility("vis") otherwise. 
The original dg-require directives were defined before there
was support for effective-target keywords.  The directives that do not
take arguments could be replaced with effective-target keywords.
     
dg-require-alias ""dg-require-ascii-locale ""dg-require-compat-dfp ""dg-require-cxa-atexit ""__cxa_atexit. 
This is equivalent to dg-require-effective-target cxa_atexit.
     dg-require-dll ""dg-require-fork ""fork.
     dg-require-gc-sections ""--gc-sections flags. 
This is equivalent to dg-require-effective-target gc-sections.
     dg-require-host-local ""-o a.out".
     dg-require-mkfifo ""mkfifo.
     dg-require-named-sections ""dg-require-effective-target named_sections.
     dg-require-weak ""dg-require-weak-override ""