Linux: Fix a bunch of clang errors from not handling return values.

Review URL: https://breakpad.appspot.com/421002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@995 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/linux/eintr_wrapper.h

@@ -44,4 +44,4 @@
   __eintr_result__;\
 })
 
-#endif // ifndef COMMON_LINUX_EINTR_WRAPPER_H_
+#endif  // COMMON_LINUX_EINTR_WRAPPER_H_

src/common/linux/ignore_ret.h

@@ -0,0 +1,40 @@
+// Copyright (c) 2012 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef COMMON_LINUX_IGNORE_RET_H_
+#define COMMON_LINUX_IGNORE_RET_H_
+
+// Some compilers are prone to warn about unused return values. In cases where
+// either a) the call cannot fail, or b) there is nothing that can be done when
+// the call fails, IGNORE_RET() can be used to mark the return code as ignored.
+// This avoids spurious compiler warnings.
+
+#define IGNORE_RET(x) do { if (x); } while (0)
+
+#endif  // COMMON_LINUX_IGNORE_RET_H_