[docs] Use relative URLs for man pages

Should have no effect on the online documentation, but it makes offline
builds more self-contained. With relative links however we have to
abstain from using `:manpage:` outside of man page cross-references.

Reviewed By: mysterymath

Differential Revision: https://reviews.llvm.org/D132794

llvm/docs/SymbolizerMarkupFormat.rst

@@ -32,8 +32,8 @@ or end of a markup element should rarely if ever appear incidentally in logging
 text. It's specifically intended not to require sanitizing plain text, such as
 the HTML/XML requirement to replace ``<`` with ``&lt;`` and the like.
 
-:manpage:`llvm-symbolizer(1)` includes a symbolizing filter via its ``--filter``
-option.
+:doc:`llvm-symbolizer <CommandGuide/llvm-symbolizer>` includes a symbolizing
+filter via its ``--filter`` option.
 
 Scope and assumptions
 =====================
@@ -431,4 +431,4 @@ over the raw logging stream, accumulating context and massaging text as it goes.
 .. rubric:: Footnotes
 
 .. [#not_yet_implemented] This markup element is not yet implemented in
-  :manpage:`llvm-symbolizer(1)`.
+  :doc:`llvm-symbolizer <CommandGuide/llvm-symbolizer>`.

llvm/docs/conf.py

@@ -236,6 +236,7 @@ basedir = os.path.dirname(__file__)
 man_page_authors = "Maintained by the LLVM Team (https://llvm.org/)."
 command_guide_subpath = 'CommandGuide'
 command_guide_path = os.path.join(basedir, command_guide_subpath)
+manpages_url = '{page}.html'
 
 
 def process_md(name):
@@ -289,6 +290,3 @@ intersphinx_mapping = {}
 # Pygment lexer are sometimes out of date (when parsing LLVM for example) or
 # wrong. Suppress the warning so the build doesn't abort.
 suppress_warnings = [ 'misc.highlighting_failure' ]
-
-# Direct html-ified man pages to llvm.org
-manpages_url = 'https://llvm.org/docs/CommandGuide/{page}.html'