include/m_string.h:
  Fix declaration of C-structure for Visual Studio and Sun C-compiler.
server-tools/instance-manager/IMService.cpp:
  Fixed.
server-tools/instance-manager/Makefile.am:
  Removed gcc-specific flags.
server-tools/instance-manager/commands.cc:
  Moved m_string.h to the header.
server-tools/instance-manager/commands.h:
  Replaced forward declaration of LEX_STRING because
  it is not understood by all compilers.
server-tools/instance-manager/instance_map.cc:
  1. Moved m_string.h to the header.
  2. Use (const char *) to point to const C-string.
server-tools/instance-manager/instance_map.h:
  Replaced forward declaration of LEX_STRING because
  it is not understood by all compilers.
server-tools/instance-manager/instance_options.h:
  Fixed headers.
server-tools/instance-manager/mysqlmanager.cc:
  Fixed headers.
server-tools/instance-manager/user_management_commands.cc:
  Removed unused variables.
server-tools/instance-manager/user_map.cc:
  Fixed headers.