Add IWYU export pragmas to gtest/gmock

This prevents clangd from complaining about unused includes from
test/gmock.h and test/gtest.h

Bug: b/42226242
Change-Id: I2bd0f61f63981dff697d60f353d198fd81ab1457
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/349480
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Auto-Submit: Evan Shrubsole <eshr@google.com>
Cr-Commit-Position: refs/heads/main@{#42200}
diff --git a/test/gmock.h b/test/gmock.h
index f137d08..9621e3e 100644
--- a/test/gmock.h
+++ b/test/gmock.h
@@ -14,7 +14,7 @@
 #include "rtc_base/ignore_wundef.h"
 
 RTC_PUSH_IGNORING_WUNDEF()
-#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gmock/include/gmock/gmock.h"  // IWYU pragma: export
 RTC_POP_IGNORING_WUNDEF()
 
 #endif  // TEST_GMOCK_H_
diff --git a/test/gtest.h b/test/gtest.h
index fa43964..68948e0 100644
--- a/test/gtest.h
+++ b/test/gtest.h
@@ -14,8 +14,10 @@
 #include "rtc_base/ignore_wundef.h"
 
 RTC_PUSH_IGNORING_WUNDEF()
+// IWYU pragma: begin_exports
 #include "testing/gtest/include/gtest/gtest-spi.h"
 #include "testing/gtest/include/gtest/gtest.h"
+// IWYU pragma: end_exports
 RTC_POP_IGNORING_WUNDEF()
 
 // GTEST_HAS_DEATH_TEST is set to 1 when death tests are supported, but appears