PR libstdc++/78905
	* doc/xml/manual/abi.xml (abi.versioning.history): Add markup to
	macro names, filenames, and literal values. Document _GLIBCXX_RELEASE.
	Document that the deprecated _GLIBCXX_VERSION macro was removed for
	the 4.0.0 release.
	* doc/html/*: Regenerate.
	* include/Makefile.am (_GLIBCXX_RELEASE): Set value.
	* include/Makefile.in: Regenerate.
	* include/bits/c++config (_GLIBCXX_RELEASE): Add #define.
	* testsuite/ext/profile/mutex_extensions_neg.cc: Use lineno of 0 in
	dg-error.

From-SVN: r244642