[clang] [clang-format] Add option to remove leading blank lines (PR #91221)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-s390x-linux` running on `systemz-1` while building `clang` at step 4 "build stage 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/42/builds/132

Here is the relevant piece of the build log for the reference:
```
Step 4 (build stage 1) failure: 'ninja -j4' (failure)
...
In file included from /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/URI.h:12,
                 from /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/Protocol.h:26,
                 from /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/FindSymbols.h:15,
                 from /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/FindSymbols.cpp:8:
In function 'clang::clangd::{anonymous}::PragmaMarkSymbol clang::clangd::{anonymous}::markToSymbol(const clang::clangd::PragmaMark&)',
    inlined from 'std::vector<clang::clangd::DocumentSymbol> clang::clangd::{anonymous}::collectDocSymbols(clang::clangd::ParsedAST&)' at /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/FindSymbols.cpp:640:35:
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/llvm/include/llvm/ADT/StringRef.h:879:20: warning: 'int __builtin_memcmp_eq(const void*, const void*, long unsigned int)' specified size 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
  879 |     return ::memcmp(LHS.data(), RHS.data(), LHS.size()) == 0;
      |            ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[148/281] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o
FAILED: tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/c++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/tools/clang/tools/extra/clangd -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/../include-cleaner/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/tools/clang/tools/extra/clangd/../clang-tidy -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/tools/clang/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/llvm/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/pseudo/lib/../include -fPIC -fvisibility-inlines-hidden -Werror=date-time -fno-lifetime-dse -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -fno-common -Woverloaded-virtual -fno-strict-aliasing -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o -MF tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o.d -o tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o -c /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/Format.cpp
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/Format.cpp: In function 'std::vector<clang::tooling::Replacement> clang::clangd::formatIncremental(llvm::StringRef, unsigned int, llvm::StringRef, clang::format::FormatStyle)':
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang-tools-extra/clangd/Format.cpp:284:11: error: 'struct clang::format::FormatStyle' has no member named 'KeepEmptyLinesAtTheStartOfBlocks'
  284 |     Style.KeepEmptyLinesAtTheStartOfBlocks = true;
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[149/281] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/DumpAST.cpp.o
[150/281] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/GlobalCompilationDatabase.cpp.o
[151/281] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/FindTarget.cpp.o
ninja: build stopped: subcommand failed.

```

https://github.com/llvm/llvm-project/pull/91221