unbreak infinite loop under valgrind more robustly

See discussion in https://github.com/gperftools/gperftools/issues/1615

This change avoids the issue even if we're unable to detect valgrind
presence.

src/malloc_extension.cc

diff --git a/src/malloc_extension.cc b/src/malloc_extension.cc
index 9934c3f..e973343 100644
--- a/src/malloc_extension.cc
+++ b/src/malloc_extension.cc
@@ -174,16 +174,8 @@
   // if MallocExtension isn't set up yet, it could be we're called
   // super-early. Trigger tcmalloc initialization and assume it will
   // set up instance().
-  if (!RunningOnValgrind()) {
-    tc_free(tc_malloc(32));
-  } else {
-    // Valgrind intercepts tc_{malloc,free}, so we do more direct
-    // "initialize the guts" procedure. We only do that for "valgrind
-    // path" because we want normal case to exercise
-    // "tc_malloc/tc_free can be called from here" behavior.
-    CHECK_CONDITION(!tcmalloc::Static::IsInited());
-    tcmalloc::ThreadCache::InitModule();
-  }
+  tcmalloc::ThreadCache::EnsureMallocInitialized();
+
   return instance();
 }
 

src/tcmalloc.cc

diff --git a/src/tcmalloc.cc b/src/tcmalloc.cc
index 32d68e6..9f372eb 100644
--- a/src/tcmalloc.cc
+++ b/src/tcmalloc.cc
@@ -1075,7 +1075,7 @@
 // ThreadCache::InitModule is not inlined which would cause nallocx to
 // become non-leaf function with stack frame and stack spills.
 static ATTRIBUTE_NOINLINE size_t nallocx_slow(size_t size, int flags) {
-  if (PREDICT_FALSE(!Static::IsInited())) ThreadCache::InitModule();
+  ThreadCache::EnsureMallocInitialized();
 
   size_t align = static_cast<size_t>(1ull << (flags & 0x3f));
   uint32_t cl;

src/thread_cache.h

diff --git a/src/thread_cache.h b/src/thread_cache.h
index 513acc4..a3aca1b 100644
--- a/src/thread_cache.h
+++ b/src/thread_cache.h
@@ -90,7 +90,13 @@
 
   bool TryRecordAllocationFast(size_t k);
 
-  static void         InitModule();
+  static void InitModule();
+  static void EnsureMallocInitialized() {
+    if (Static::IsInited()) {
+      return;
+    }
+    InitModule();
+  }
 
   // Return the number of thread heaps in use.
   static inline int HeapsInUse();