lib: move all UNITTEST prototypes to C files

- make extract-unit-protos handle multi-line prototypes - but they need
  to be above the implementation

- Prototypes for static functions we use in unit tests should not be in
  header files. We generate lib/unitprotos.h for this purpose

- Removed some function wrappers written for unit tests and make them
  use UNITTEST function directly.

- Renamed time2str() in the tool to timebuf() since we have the same
  name in lib/ and in unit tests they can both be used non-static in a
  build.

This reverts commit f95fadd116.

Follow-up to #21010

Closes #21014

scripts/extract-unit-protos

@@ -27,15 +27,38 @@ use strict;
 use warnings;
 
 my @proto;
+my %func;
 my %inc;
 
 sub scanfile {
     my ($file) = @_;
     open(F, "<$file") || die "$file failed";
+    my $unit = 0;
     while(<F>) {
-        if($_ =~ /^UNITTEST .*\);/) {
-            push @proto, $_;
-            $inc{$file} = 1;
+        if($_ =~ /^UNITTEST .*[* ]([a-z0-9_]+)\(/i) {
+            my $n = $1;
+            if($func{$n}) {
+                # already prototyped, this is now the function itself
+            }
+            else {
+                $func{$n} = 1;
+                push @proto, $_;
+                $inc{$file} = 1;
+                $unit = 1;
+            }
+        }
+        if($unit) {
+            if($unit != 1) {
+                push @proto, $_;
+            }
+            if($_ =~ /\);/) {
+                # end of proto
+                $unit = 0;
+            }
+            else {
+                # proto continues
+                $unit++;
+            }
         }
     }
     close(F);