[LatencyPriorityQueue] Fix build: missing override

[10/260] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PostRASchedulerList.cpp.o
FAILED: lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PostRASchedulerList.cpp.o
/usr/local/bin/clang++  -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/CodeGen -I/build/llvm/lib/CodeGen -I/usr/include/libxml2 -Iinclude -I/build/llvm/include -g0 -fPIC -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fcolor-diagnostics -ffunction-sections -fdata-sections -O3 -g0  -fPIC   -UNDEBUG  -fno-exceptions -fno-rtti -MD -MT lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PostRASchedulerList.cpp.o -MF lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PostRASchedulerList.cpp.o.d -o lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/PostRASchedulerList.cpp.o -c /build/llvm/lib/CodeGen/PostRASchedulerList.cpp
In file included from /build/llvm/lib/CodeGen/PostRASchedulerList.cpp:26:
/build/llvm/include/llvm/CodeGen/LatencyPriorityQueue.h:87:27: error: 'dump' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
    LLVM_DUMP_METHOD void dump(ScheduleDAG *DAG) const {
                          ^
/build/llvm/include/llvm/CodeGen/ScheduleDAG.h:547:18: note: overridden virtual function is here
    virtual void dump(ScheduleDAG *) const {}
                 ^
1 error generated.

llvm-svn: 330119