gralloc960/mali_gralloc_debug.cpp: migrate to String8.c_str()

as suggested by the commit here:
otherwise the following build error will be reported:
    device/linaro/hikey/gralloc960/mali_gralloc_debug.cpp:140:34: error: 'string' is a private member of 'android::String8'
                            memcpy(outBuffer, dumpStrings.string(), *outSize);
    system/core/libutils/include/utils/String8.h:157:33: note: declared private here
        inline  const char*         string() const;
    1 error generated.

Test: build successfully and boot to the homescreen

Change-Id: Id7ba2ef926534cc8225450439e53258a19d5c21e
Signed-off-by: Amit Pundir <>
Signed-off-by: Yongqin Liu <>
1 file changed