recovery: turn on text display for install errors in debug builds

Hopefully this will reduce the number of OTA "bugs" reported that are
really just someone having changed their system partition,
invalidating future incremental OTAs.

Also fixes a longstanding TODO about putting LOGE() output in the
on-screen display.

Change-Id: I44e5be65b2dee7ebce2cce28ccd920dc3d6e522e

verifier_test.cpp

@@ -18,6 +18,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 
+#include "common.h"
 #include "verifier.h"
 #include "ui.h"
 #include "mincrypt/sha.h"
@@ -115,13 +116,10 @@ class FakeUI : public RecoveryUI {
     bool IsTextVisible() { return false; }
     bool WasTextEverVisible() { return false; }
     void Print(const char* fmt, ...) {
-        char buf[256];
         va_list ap;
         va_start(ap, fmt);
-        vsnprintf(buf, 256, fmt, ap);
+        vfprintf(stderr, fmt, ap);
         va_end(ap);
-
-        fputs(buf, stderr);
     }
 
     void StartMenu(const char* const * headers, const char* const * items,
@@ -130,6 +128,14 @@ class FakeUI : public RecoveryUI {
     void EndMenu() { }
 };
 
+void
+ui_print(const char* format, ...) {
+    va_list ap;
+    va_start(ap, format);
+    vfprintf(stdout, format, ap);
+    va_end(ap);
+}
+
 int main(int argc, char **argv) {
     if (argc < 2 || argc > 4) {
         fprintf(stderr, "Usage: %s [-sha256] [-f4 | -file <keys>] <package>\n", argv[0]);