Remove checks for _USING_LIBCXX

__cplusplus is enough

Test: build
Change-Id: Ia0cf3b5beafe41ae1ce17335b5b06c753e665a32
diff --git a/liblog/include/log/log_event_list.h b/liblog/include/log/log_event_list.h
index 1b7c377..8f7c421 100644
--- a/liblog/include/log/log_event_list.h
+++ b/liblog/include/log/log_event_list.h
@@ -20,10 +20,8 @@
 #include <errno.h>
 #include <stdint.h>
 
-#if (defined(__cplusplus) && defined(_USING_LIBCXX))
-extern "C++" {
+#ifdef __cplusplus
 #include <string>
-}
 #endif
 
 #include <log/log.h>
@@ -208,14 +206,12 @@
     return *this;
   }
 
-#if defined(_USING_LIBCXX)
   android_log_event_list& operator<<(const std::string& value) {
     int retval =
         android_log_write_string8_len(ctx, value.data(), value.length());
     if (retval < 0) ret = retval;
     return *this;
   }
-#endif
 
   android_log_event_list& operator<<(float value) {
     int retval = android_log_write_float32(ctx, value);
@@ -269,7 +265,6 @@
     return ret >= 0;
   }
 
-#if defined(_USING_LIBCXX)
   bool AppendString(const std::string& value) {
     int retval =
         android_log_write_string8_len(ctx, value.data(), value.length());
@@ -283,7 +278,6 @@
     if (retval < 0) ret = retval;
     return ret;
   }
-#endif
 
   bool AppendFloat(float value) {
     int retval = android_log_write_float32(ctx, value);
diff --git a/liblog/include/private/android_logger.h b/liblog/include/private/android_logger.h
index b927b46..9da20a6 100644
--- a/liblog/include/private/android_logger.h
+++ b/liblog/include/private/android_logger.h
@@ -25,10 +25,8 @@
 #include <stdint.h>
 #include <sys/types.h>
 
-#if (defined(__cplusplus) && defined(_USING_LIBCXX))
-extern "C++" {
+#ifdef __cplusplus
 #include <string>
-}
 #endif
 
 #include <log/log.h>
@@ -170,7 +168,6 @@
       : android_log_event_list(log_msg) {
   }
 
-#if defined(_USING_LIBCXX)
   operator std::string() {
     if (ret) return std::string("");
     const char* cp = nullptr;
@@ -179,7 +176,6 @@
     if (!cp || (len <= 0)) return std::string("");
     return std::string(cp, len);
   }
-#endif
 };
 }
 #endif