Add a way to print the full command line being executed by the launcher

.github/workflows/wheel.yaml

@@ -85,6 +85,8 @@ jobs:
         set -ex
         cat .venv/Scripts/rez/rez-script.py
         cat .venv/Scripts/rez/jctest-script.py
+        export REZ_LAUNCHER_DEBUG=1
+
         jctest
 
         rez --help

launcher/remote-appended.patch

@@ -1,14 +1,27 @@
-diff --git a/launcher.c b/launcher.c
-index 727f7916..2447d378 100644
---- a/launcher.c
-+++ b/launcher.c
-@@ -35,8 +35,6 @@
-
- #pragma comment (lib, "Shlwapi.lib")
-
--#define APPENDED_ARCHIVE
--#define USE_ENVIRONMENT
- #define SUPPORT_RELATIVE_PATH
-
- #define MSGSIZE 1024
-
+diff --git a/launcher/launcher.c b/launcher/launcher.c
+index 727f7916..431e0339 100644
+--- a/launcher/launcher.c
++++ b/launcher/launcher.c
+@@ -35,8 +35,6 @@
+
+ #pragma comment (lib, "Shlwapi.lib")
+
+-#define APPENDED_ARCHIVE
+-#define USE_ENVIRONMENT
+ #define SUPPORT_RELATIVE_PATH
+
+ #define MSGSIZE 1024
+@@ -822,6 +820,13 @@ run_child(wchar_t * cmdline)
+ #endif
+         si.dwFlags |= STARTF_USESTDHANDLES;
+     }
++
++    size_t rez_envvar_size = 0;
++    getenv_s(&rez_envvar_size, NULL, 0, "REZ_LAUNCHER_DEBUG");
++    if (rez_envvar_size > 0) {
++        printf("Launching: %ls\n", cmdline);
++    }
++
+     ok = CreateProcessW(NULL, cmdline, NULL, NULL, TRUE, 0, NULL, NULL, &si, &child_process_info);
+     if (!ok) {
+         // Failed to create process. See if we can find out why.