ifdef __cplusplus spinlock and condvar constructors.

So scale-amd64 can build lwIP again..

ifdef __cplusplus spinlock and condvar constructors.
cbe04cd9 · Silas Boyd-Wickizer · 85628dc5 · cbe04cd9 · cbe04cd9
--- a/include/condvar.h
+++ b/include/condvar.h
@@ -6,6 +6,7 @@ struct condvar {
  struct spinlock lock;
  LIST_HEAD(waiters, proc) waiters;

+#ifdef __cplusplus
  // Create a condvar that will later be initialized by initcondvar.
  // XXX(austin) Remove this and initcondvar.
  constexpr condvar()
@@ -14,4 +15,5 @@ struct condvar {
  constexpr
  condvar(const char *name)
    : lock(name, LOCKSTAT_CONDVAR), waiters{} { }
+#endif // __cplusplus
 };
--- a/include/spinlock.h
+++ b/include/spinlock.h
@@ -21,6 +21,7 @@ struct spinlock {
  struct klockstat *stat;
 #endif

+#ifdef __cplusplus
  // Create a spinlock that will later be initialized by initlock.
  // XXX(austin) Remove this and initlock in favor of the other ctor.
  constexpr spinlock()
@@ -44,6 +45,7 @@ struct spinlock {
    , stat(lockstat ? nullptr : &klockstat_lazy)
 #endif
  { }
+#endif // __cplusplus
 };

 #if SPINLOCK_DEBUG