Issue #15527: remove double parens by changing markup.

Patch by Serhiy Storchaka.
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 9caebf1..5bfa351 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -329,7 +329,7 @@
 
 .. function:: setpgrp()
 
-   Call the system call :c:func:`setpgrp` or :c:func:`setpgrp(0, 0)` depending on
+   Call the system call :c:func:`setpgrp` or ``setpgrp(0, 0)`` depending on
    which version is implemented (if any).  See the Unix manual for the semantics.
 
    Availability: Unix.
diff --git a/Doc/library/platform.rst b/Doc/library/platform.rst
index 28b6f08..9f64095 100644
--- a/Doc/library/platform.rst
+++ b/Doc/library/platform.rst
@@ -33,8 +33,8 @@
    returned as strings.
 
    Values that cannot be determined are returned as given by the parameter presets.
-   If bits is given as ``''``, the :c:func:`sizeof(pointer)` (or
-   :c:func:`sizeof(long)` on Python version < 1.5.2) is used as indicator for the
+   If bits is given as ``''``, the ``sizeof(pointer)`` (or
+   ``sizeof(long)`` on Python version < 1.5.2) is used as indicator for the
    supported pointer size.
 
    The function relies on the system's :file:`file` command to do the actual work.