I had to do this to get my build to work.
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 5d96e5fd..140ff807 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -2196,7 +2196,7 @@ continues.
@itemx --with-target-bdw-gc-lib=@var{list}
Specify search directories for the garbage collector header files and
libraries. @var{list} is a comma separated list of key value pairs of the
-form @samp{@var{multilibdir}@=@var{path}}, where the default multilib key
+form @samp{@var{multilibdir}=@var{path}}, where the default multilib key
is named as @samp{.} (dot), or is omitted (e.g.
@samp{--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32}).
The error was:
../../trunk/gcc/doc/install.texi:2199: use braces to give a command as
an argument to @=
make[2]: *** [doc/gccinstall.info] Error 1
make[1]: *** [all-gcc] Error 2
make: *** [all] Error 2
I do not know who is to fix.