Remove spurious exit() calls from configure.ac

We added these a while ago, but they do no actual good, and
cause implicit declaration warnings in some situations.  Rather than
just adding stdint.h, it's easier to remove the exit() calls
as redundant.

Fixes bug 18626; bugfix from "cypherpunks"

changes/bug18626

+  o Minor bugfixes (build):
+    - Avoid spurious failures from configure files related
+      to calling exit(0) in TOR_SEARCH_LIBRARY.
+      Fixes bug 18625; bugfix on 0.2.0.1-alpha.
+      Patch from "cypherpunks".

configure.ac

@@ -473,19 +473,18 @@ TOR_SEARCH_LIBRARY(libevent, $trylibeventdir, [-levent $STATIC_LIBEVENT_FLAGS $T
 #ifdef _WIN32
 #include <winsock2.h>
 #endif
-#include <stdlib.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <event.h>], [
 #ifdef _WIN32
 #include <winsock2.h>
 #endif
-void exit(int); void *event_init(void);],
+void *event_init(void);],
     [
 #ifdef _WIN32
 {WSADATA d; WSAStartup(0x101,&d); }
 #endif
-event_init(); exit(0);
+event_init();
 ], [--with-libevent-dir], [/opt/libevent])
 
 dnl Now check for particular libevent functions.
@@ -611,7 +610,7 @@ AC_ARG_WITH(ssl-dir,
 TOR_SEARCH_LIBRARY(openssl, $tryssldir, [-lssl -lcrypto $TOR_LIB_GDI],
     [#include <openssl/rand.h>],
     [void RAND_add(const void *buf, int num, double entropy);],
-    [RAND_add((void*)0,0,0); exit(0);], [],
+    [RAND_add((void*)0,0,0);], [],
     [/usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/athena /opt/openssl])
 
 dnl XXXX check for OPENSSL_VERSION_NUMBER == SSLeay()
@@ -688,7 +687,7 @@ tor_zlib_devpkg_debian="zlib1g-dev"
 TOR_SEARCH_LIBRARY(zlib, $tryzlibdir, [-lz],
     [#include <zlib.h>],
     [const char * zlibVersion(void);],
-    [zlibVersion(); exit(0);], [--with-zlib-dir],
+    [zlibVersion();], [--with-zlib-dir],
     [/opt/zlib])
 
 if test "$enable_static_zlib" = "yes"; then