[lld] Clean up in lld::{coff,elf}::link after D70378

Library users should not need to call errorHandler().reset() explicitly.

google/iree calls lld::elf::link and without the patch some global
variables are not cleaned up in the next invocation.

Author: MaskRay

lld/COFF/Driver.cpp

@@ -96,7 +96,10 @@ bool link(ArrayRef<const char *> args, bool canExitEarly, raw_ostream &stdoutOS,
   if (canExitEarly)
     exitLld(errorCount() ? 1 : 0);
 
-  return !errorCount();
+  bool ret = errorCount() == 0;
+  if (!canExitEarly)
+    errorHandler().reset();
+  return ret;
 }
 
 // Parse options of the form "old;new".

lld/ELF/Driver.cpp

@@ -125,7 +125,10 @@ bool elf::link(ArrayRef<const char *> args, bool canExitEarly,
   if (canExitEarly)
     exitLld(errorCount() ? 1 : 0);
 
-  return !errorCount();
+  bool ret = errorCount() == 0;
+  if (!canExitEarly)
+    errorHandler().reset();
+  return ret;
 }
 
 // Parses a linker -m option.