Fix typography of "C." (spacing)

Author: tkoeppe

source/compatibility.tex

@@ -108,7 +108,7 @@
 is valid in C, invalid in \Cpp.
 This makes it impossible to define
 mutually referential file-local static objects, if initializers are
-restricted to the syntactic forms of C.
+restricted to the syntactic forms of C\@.
 For example,
 
 \begin{codeblock}
@@ -788,7 +788,7 @@
 \change Whether \mname{STDC} is defined and if so, what its value is, are
 implementation-defined
 \rationale
-\Cpp is not identical to ISO C.
+\Cpp is not identical to ISO C\@.
 Mandating that \mname{STDC}
 be defined would require that translators make an incorrect claim.
 Each implementation must choose the behavior that will be most

source/intro.tex

@@ -403,7 +403,7 @@
 \pnum
 Annex~\ref{diff} summarizes the evolution of \Cpp  since its first
 published description, and explains in detail the differences between
-\Cpp  and C. Certain features of \Cpp  exist solely for compatibility
+\Cpp  and C\@. Certain features of \Cpp  exist solely for compatibility
 purposes; Annex~\ref{depr} describes those features.
 
 \pnum