Convert man page from roff to DocBook.

Convert the man page source from roff to DocBook, and generate html and
roff output.  Modify the build system such that the documentation can be
built as part of the release process, so that users need not have
DocBook tools installed.

jemalloc/INSTALL

@@ -132,8 +132,11 @@ any of the following arguments (not a definitive list) to 'configure':
 --disable-tls
     Disable thread-local storage (TLS), which allows for fast access to
     thread-local variables via the __thread keyword.  If TLS is available,
-    jemalloc uses it for several purposes.  Note that disabling TLS implies
-    --disable-tcache.
+    jemalloc uses it for several purposes.
+
+--with-xslroot=<path>
+    Specify where to find DocBook XSL stylesheets when building the
+    documentation.
 
 The following environment variables (not a definitive list) impact configure's
 behavior:
@@ -172,7 +175,7 @@ To install only parts of jemalloc, use the following targets:
     install_bin
     install_include
     install_lib
-    install_man
+    install_doc
 
 To clean up build results to varying degrees, use the following make targets:
 
@@ -232,11 +235,12 @@ directory, issue configuration and build commands:
 
 === Documentation ==============================================================
 
-The manual page that the configure script generates can be manually formatted
+The manual page is generated in both html and roff formats.  Any web browser
+can be used to view the html manual.  The roff manual page can be formatted
 prior to installation via any of the following commands:
 
-    nroff -man -man-ext -t doc/jemalloc.3
+    nroff -man -t doc/jemalloc.3
 
-    groff -man -man-ext -t -Tps doc/jemalloc.3 | ps2pdf - doc/jemalloc.3.pdf
+    groff -man -t -Tps doc/jemalloc.3 | ps2pdf - doc/jemalloc.3.pdf
 
     (cd doc; groff -man -man-ext -t -Thtml jemalloc.3 > jemalloc.3.html)