Add modula-2 into doc/install.texi and doc/sourcebuild.texi.

Add modula-2 into doc/install.texi and doc/sourcebuild.texi.

gcc/ChangeLog:

	* doc/install.texi: Add m2 as a language.
	(--disable-libgm2) Documented.  Add make check-m2 to
	testing selected tests.
	* doc/sourcebuild.texi (GM2): New prerequisite item.
        (Python3 modules) New item.  (libgm2) Added.
	(gcc/m2) Added.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index a085f65..8d66f20 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1888,11 +1888,13 @@
 @end smallexample
 Currently, you can use any of the following:
 @code{all}, @code{default}, @code{ada}, @code{c}, @code{c++}, @code{d},
-@code{fortran}, @code{go}, @code{jit}, @code{lto}, @code{objc}, @code{obj-c++}.
+@code{fortran}, @code{go}, @code{jit}, @code{lto}, @code{m2},
+@code{objc}, @code{obj-c++}.
 Building the Ada compiler has special requirements, see below.
 If you do not pass this flag, or specify the option @code{default}, then the
 default languages available in the @file{gcc} sub-tree will be configured.
-Ada, D, Go, Jit, and Objective-C++ are not default languages.  LTO is not a
+Ada, D, Go, Jit, Objective-C++ and Modula-2 are not default languages.
+LTO is not a
 default language, but is built by default because @option{--enable-lto} is
 enabled by default.  The other languages are default languages.  If
 @code{all} is specified, then all available languages are built.  An
@@ -1920,6 +1922,10 @@
 previous Ada build procedures, when it was required to explicitly
 do a @samp{make -C gcc gnatlib_and_tools}.
 
+@item --disable-libgm2
+Specify that the run-time libraries and tools used by Modula-2 should not
+be built.  This can be useful for debugging.
+
 @item --disable-libsanitizer
 Specify that the run-time libraries for the various sanitizers should
 not be built.
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index ffe69d6..562be48 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -97,6 +97,9 @@
 @item libgfortran
 The Fortran runtime library.
 
+@item libgm2
+The Modula-2 runtime library.
+
 @item libgo
 The Go runtime library.  The bulk of this library is mirrored from the
 @uref{https://github.com/@/golang/go, master Go repository}.
@@ -184,7 +187,8 @@
 @item @var{language}
 Subdirectories for various languages.  Directories containing a file
 @file{config-lang.in} are language subdirectories.  The contents of
-the subdirectories @file{c} (for C), @file{cp} (for C++),
+the subdirectories @file{c} (for C), @file{cp} (for C++), @file{m2}
+(for Modula-2),
 @file{objc} (for Objective-C), @file{objcp} (for Objective-C++),
 and @file{lto} (for LTO) are documented in this
 manual (@pxref{Passes, , Passes and Files of the Compiler});