fix: diagnose embedded library initialization

ober

0c5a837b74b54b7d2a103667ab2e10deda40a390

diff --git a/support/multicall-main.c b/support/multicall-main.c
index 27b47e3..60a00da 100644
--- a/support/multicall-main.c
+++ b/support/multicall-main.c
@@ -90,7 +90,12 @@ static mode_t jerboa_umask(mode_t mode) {
 #endif
 
 static void call_scheme_1(const char *who, ptr arg) {
-    Scall1(Stop_level_value(Sstring_to_symbol(who)), arg);
+    ptr procedure = Stop_level_value(Sstring_to_symbol(who));
+    if (getenv("JERBOA_DEBUG_BOOT") != NULL) {
+        fprintf(stderr, "jerboa: calling %s (procedure=%d)\n", who,
+                Sprocedurep(procedure) ? 1 : 0);
+    }
+    Scall1(procedure, arg);
 }
 
 /* ── jerbuild lib bundle: extracted to a per-sha cache dir on demand ───────