[NFC][sanitizer] Remove unneeded "explicit"

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -592,7 +592,7 @@ class InternalMmapVector : public InternalMmapVectorNoCtor<T> {
 
 class InternalScopedString {
  public:
-  explicit InternalScopedString() : buffer_(1) { buffer_[0] = '\0'; }
+  InternalScopedString() : buffer_(1) { buffer_[0] = '\0'; }
 
   uptr length() const { return buffer_.size() - 1; }
   void clear() {