Merge r1888017 from trunk:

Follow up to r1887279: fix new APR_TRY_COMPILE_NO_WARNING.

AC_LANG_PROGRAM generates an "int main()" prototype which some compilers warn
about. Restore AC_LANG_SOURCE to manually set the correct main() but do not
#include "confdefs.h" if it is inlined already by AC_LANG_SOURCE (i.e.
check whether PACKAGE_NAME is already defined).

Github: closes #25


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.7.x@1888018 13f79535-47bb-0310-9956-ffa450edef68

Author: ylavic

build/apr_common.m4

@@ -467,9 +467,16 @@ AC_DEFUN([APR_TRY_COMPILE_NO_WARNING],
    CFLAGS="$CFLAGS -Werror"
  fi
  AC_COMPILE_IFELSE(
-  [AC_LANG_PROGRAM(
-   [[$1]],
+  [AC_LANG_SOURCE(
+   [
+#ifndef PACKAGE_NAME
+#include "confdefs.h"
+#endif
+   ]
+   [[$1]]
+   [int main(int argc, const char *const *argv) {]
    [[$2]]
+   [   return 0; }]
   )], [CFLAGS=$apr_save_CFLAGS
 $3],  [CFLAGS=$apr_save_CFLAGS
 $4])