execute, spawn-pipe: Support DLL dependencies of Windows executables. Reported by Michele Locati <michele@locati.it>. * lib/windows-path.h: New file. * lib/windows-path.c: New file. * lib/windows-spawn.h (compose_envblock): Add new_PATH parameter. (spawnpvech): Add dll_dirs parameter. Call extended_PATH. * lib/windows-spawn.c: Include windows-path.h. (compose_envblock): Add new_PATH parameter. * modules/windows-spawn (Description): Now applies to Cygwin as well. (Files): Add lib/windows-path.h, lib/windows-path.c. (configure.ac): Define GL_COND_OBJ_WINDOWS_PATH. (Makefile.am): Conditionally compile windows-path.c. (Include): Add windows-path.h. * lib/spawni.c (__spawni): Update compose_envblock call. * lib/execute.h (execute): Add dll_dirs parameter. * lib/execute.c: Include windows-path.h. (execute): Add dll_dirs parameter. Pass it down to spawnpvech. Call extended_environ. * lib/spawn-pipe.h (create_pipe_out, create_pipe_in, create_pipe_bidi): Add dll_dirs parameter. * lib/spawn-pipe.c: Include windows-path.h. (create_pipe): Add dll_dirs parameter. Pass it down to spawnpvech. Call extended_environ. (create_pipe_bidi, create_pipe_in, create_pipe_out): Add dll_dirs parameter. * lib/javaexec.c (execute_java_class): Update execute invocations. * lib/cygpath.c (execute_and_read_line): Update create_pipe_in invocation. * lib/javaversion.c (execute_and_read_line): Likewise. * lib/csharpcomp.c (compile_csharp_using_mono, compile_csharp_using_dotnet, compile_csharp_using_sscli): Update execute, create_pipe_in invocations. * lib/csharpexec.c (execute_csharp_using_mono, execute_csharp_using_dotnet, execute_csharp_using_sscli): Likewise. * lib/javacomp.c (compile_using_envjavac, compile_using_javac, execute_and_read_line, is_javac_present): Likewise. * lib/pipe-filter-gi.c (pipe_filter_gi_create): Update create_pipe_bidi invocation. * lib/pipe-filter-ii.c (pipe_filter_ii_execute): Likewise. * tests/test-execute-main.c (main): Update execute invocations. * tests/test-execute-script.c (main): Likewise. * tests/test-spawn-pipe-main.c (main): Update create_pipe_bidi invocation. * tests/test-spawn-pipe-script.c (main): Update create_pipe_in invocations. * NEWS: Mention the changes.