Added needed C header includes

[SVN r21334]

example/jgrep/main.cpp

@@ -16,6 +16,7 @@
 
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <boost/regex.hpp>
 #ifdef JM_OLD_IOSTREAM
 #include <iostream.h>

test/c_compiler_checks/wide_posix_api_check.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <assert.h>
 #include <wchar.h>
+#include <stdlib.h>
 #include <boost/regex.h>
 
 #ifndef BOOST_NO_WREGEX

test/c_compiler_checks/wide_posix_api_check.cpp

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <assert.h>
 #include <wchar.h>
+#include <stdlib.h>
 #include <boost/regex.h>
 
 #ifndef BOOST_NO_WREGEX

test/concepts/concept_check.cpp

@@ -18,6 +18,7 @@
 #endif
 #include <boost/concept_check.hpp>
 #include <boost/detail/workaround.hpp>
+#include <cstdlib>
 
 
 int main()