style(cli): preserve C90 declaration ordering

Move the decompression-resource state declaration ahead of the first
statement in FIO_createDResources.  The initializer only captures the
resource address, so moving memset after the declaration preserves the
runtime order while avoiding the ISO C90 mixed-declaration warning.

Test Plan:
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 make -j1 (passed after cleanup)
- ulimit -v 41943040; CARGO_BUILD_JOBS=1 make -j1 -C tests test (passed before this declaration-only cleanup)
- git diff --check (passed)

programs/fileio.c

@@ -4006,8 +4006,6 @@ static int FIO_rust_createDResources_isError(size_t result)
 static dRess_t FIO_createDResources(FIO_prefs_t* const prefs, const char* dictFileName)
 {
     dRess_t ress;
-    memset(&ress, 0, sizeof(ress));
-
     FIO_rust_createDResourcesState const state = {
         &ress,
         prefs,
@@ -4021,6 +4019,7 @@ static dRess_t FIO_createDResources(FIO_prefs_t* const prefs, const char* dictFi
         FIO_rust_createDResources_createReadPool,
         FIO_rust_createDResources_isError
     };
+    memset(&ress, 0, sizeof(ress));
     CHECK(FIO_rust_createDResources(&state));
     return ress;
 }