Some changes to the compiler require that a user trying to build and install

Estimated hours taken: 1

Some changes to the compiler require that a user trying to build and install
a new version of the compiler from Mercury sources do the `mmake install'
step from the stage 2 directory.  This was not mentioned in the INSTALL_CVS;
this change fixes that omission.

INSTALL_CVS:
	Now runs a bootcheck by default and performs the `mmake install'
	from the stage 2 directory.  Updated the instructions to tell the
	user how to install without the bootcheck, and the implications of
	doing this.

INSTALL_CVS

@@ -16,10 +16,24 @@
 #
 # Step 3.  mmake
 #
-# Step 4.  mmake install
+# Step 4.  tools/bootcheck
+#
+# Step 5.  cd stage2 && mmake install
 #
 #	   If you just want to do a `make' rather than a `make install',
 #	   then comment out the `mmake install' line below.
+#
+#	   If you want to install without doing a boot check, then comment
+#	   out the `tools/bootcheck' and `cd stage2' lines below.  If the
+#	   version of the compiler you checked out is buggy and you don't
+#	   perform a boot check first, you risk installing a version of the
+#	   compiler incapable of compiling itself.  Make sure you have a
+#	   fall-back plan if you do this.
+#	   Note also that occasionally changes made to the compiler mean
+#	   that installing from a stage 1 build will fail, even when the
+#	   compiler is fine.  In such cases the only way to install the
+#	   compiler is from the stage 2 directory.
+#
 #	   If you don't want to do a parallel make, comment out the
 #	   `parallel=-j3' line below.
 
@@ -30,5 +44,7 @@ autoconf &&
 touch Mmake.params &&
 mmake depend $parallel &&
 mmake MMAKEFLAGS=$parallel &&
+tools/bootcheck $parallel &&
+cd stage2 &&
 mmake install MMAKEFLAGS=$parallel &&
 true