Reduce stack pressure throughout Cygwin

* dcrt0.cc (initial_env): Reduce size of local path buffers to
        PATH_MAX.  Allocate debugger_command from process heap.
        (init_windows_system_directory): Very early initialize new global
        variable global_progname.
        * dll_init.cc (dll_list::alloc): Make path buffer static.  Explain why.
        (dll_list::populate_deps): Use tmp_pathbuf for local path buffer.
        * exceptions.cc (debugger_command): Convert to PWCHAR.
        (error_start_init): Allocate debugger_command and fill with wide char
        strings.  Only allocate if NULL.
        (try_to_debug): Just check if debugger_command is a NULL pointer to
        return.  Drop conversion from char to WCHAR and drop local variable
        dbg_cmd.
        * globals.cc (global_progname): New global variable to store Windows
        application path.
        * pinfo.cc (pinfo_basic::pinfo_basic): Just copy progname over from
        global_progname.
        (pinfo::status_exit): Let path_conv create the POSIX path to
        avoid local buffer.
        * pseudo_reloc.cc (__report_error): Utilize global_progname, drop local
        buffer.
        * smallprint.cc (__small_vsprintf): Just utilize global_progname for
        %P format specifier.
        (__small_vswprintf): Ditto.
        * strace.cc (PROTECT): Change to reflect x being a pointer.  Reformat.
        (CHECK): Ditto.  Reformat.
        (strace::activate): Utilize global_progname, drop local buffer.
        Fix formatting.
        (strace::vsprntf): Reduce size of local progname buffer to NAME_MAX.
        Copy and, if necessary, convert only the last path component to
        progname.
        (strace_buf_guard): New muto.
        (buf): New static pointer.
        (strace::vprntf): Use buf under strace_buf_guard lock only.  Allocate
        buffer space for buf on Windows heap.
        * wow64.cc (wow64_respawn_process): Utilize global_progname, drop
        local path buffer.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/dll_init.cc

@@ -25,6 +25,7 @@ details. */
 #include <wchar.h>
 #include <sys/reent.h>
 #include <assert.h>
+#include <tls_pbuf.h>
 
 extern void __stdcall check_sanity_and_sync (per_process *);
 
@@ -178,7 +179,9 @@ dll_list::find_by_modname (const PWCHAR modname)
 dll *
 dll_list::alloc (HINSTANCE h, per_process *p, dll_type type)
 {
-  WCHAR buf[NT_MAX_PATH];
+  /* Called under loader lock conditions so this function can't be called
+     multiple times in parallel.  A static buffer is safe. */
+  static WCHAR buf[NT_MAX_PATH];
   GetModuleFileNameW (h, buf, NT_MAX_PATH);
   PWCHAR name = buf;
   if (!wcsncmp (name, L"\\\\?\\", 4))
@@ -264,7 +267,9 @@ dll_list::append (dll* d)
 
 void dll_list::populate_deps (dll* d)
 {
-  WCHAR wmodname[NT_MAX_PATH];
+  tmp_pathbuf tp;
+
+  PWCHAR wmodname = tp.w_get ();
   pefile* pef = (pefile*) d->handle;
   PIMAGE_DATA_DIRECTORY dd = pef->idata_dir (IMAGE_DIRECTORY_ENTRY_IMPORT);
   /* Annoyance: calling crealloc with a NULL pointer will use the