Warnings when building on Fedora linux

[Benson Muite]

Some warnings when building for inclusion on Fedora linux with compiler options:
-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer

/builddir/build/BUILD/glsl-language-server-0.4.1/src/messagebuffer.cpp: In member function 'void MessageBuffer::handle_char(char)':
/builddir/build/BUILD/glsl-language-server-0.4.1/src/messagebuffer.cpp:31:36: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   31 |         if (m_raw_message.length() == content_length) {
      |             ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
/builddir/build/BUILD/glsl-language-server-0.4.1/src/messagebuffer.cpp: In member function 'void MessageBuffer::handle_string(std::string)':
/builddir/build/BUILD/glsl-language-server-0.4.1/src/messagebuffer.cpp:62:36: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   62 |         if (m_raw_message.length() == content_length) {
      |             ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

/builddir/build/BUILD/glsl-language-server-0.4.1/src/symbols.cpp: In function 'void extract_symbols(const char*, SymbolMap&, const char*)':
/builddir/build/BUILD/glsl-language-server-0.4.1/src/symbols.cpp:192:25: warning: variable 'end' set but not used [-Wunused-but-set-variable]
  192 |             const char* end = nullptr;
      |                         ^~~
/builddir/build/BUILD/glsl-language-server-0.4.1/src/symbols.cpp:125:10: warning: variable 'had_arguments' set but not used [-Wunused-but-set-variable]
  125 |     bool had_arguments = false;
      |          ^~~~~~~~~~~~~