[rand, atomics] Don't needlessly escape underscores. (#1568)

The 'underscore' package already makes '_' in text behave as \_.

Author: Eelis

source/atomics.tex

@@ -1239,7 +1239,7 @@
 \end{itemdecl}
 
 \begin{itemdescr}
-\effects Equivalent to: \tcode{return fetch\_add(1);}
+\effects Equivalent to: \tcode{return fetch_add(1);}
 \end{itemdescr}
 
 \indexlibrarymember{operator\dcr}{atomic<T*>}%
@@ -1250,7 +1250,7 @@
 \end{itemdecl}
 
 \begin{itemdescr}
-\effects Equivalent to: \tcode{return fetch\_sub(1);}
+\effects Equivalent to: \tcode{return fetch_sub(1);}
 \end{itemdescr}
 
 \indexlibrarymember{operator++}{atomic<T*>}%

source/numerics.tex

@@ -1435,7 +1435,7 @@
 If integer-valued,
 an entity may optionally be further characterized as
 \techterm{signed} or \techterm{unsigned},
-according to \tcode{numeric\_limits<T>::is\_signed}.
+according to \tcode{numeric_limits<T>::is_signed}.
 
 \pnum
 Unless otherwise specified,