Revert "increase StackChecker maximum to 256KB. used for _DEBUG builds"

This reverts commit 4cc8a4b.
Broke Linux 32-bit debug builds -- "test" is segfaulting in StackChecker
SERVER-5804

src/mongo/db/client.cpp

@@ -48,8 +48,9 @@ namespace mongo {
 #if defined(_DEBUG)
     struct StackChecker;
     ThreadLocalValue<StackChecker *> checker;
+
     struct StackChecker { 
-        enum { SZ = 256 * 1024 };
+        enum { SZ = 192 * 1024 };
         char buf[SZ];
         StackChecker() { 
             checker.set(this);
@@ -74,18 +75,15 @@ namespace mongo {
                 log() << "thread " << tname << " stack usage was " << numberBytesUsed << " bytes, " 
                       << " which is the most so far" << endl;
             }
-
+            
             if ( numberBytesUsed > ( SZ - 16000 ) ) {
                 // we are within 16000 bytes of SZ
-                log() << "stack used " << numberBytesUsed << " bytes, StackChecker max is " << (int)SZ << " exiting" << endl;
+                log() << "used " << numberBytesUsed << " bytes, max is " << (int)SZ << " exiting" << endl;
                 fassertFailed( 16151 );
             }
 
         }
     };
-    void stackCheck(const char *name) { StackChecker::check(name); }
-#else
-    void stackCheck(const char *) {}
 #endif
 
     /* each thread which does db operations has a Client object in TLS.

src/mongo/dbtests/perftests.cpp

@@ -42,7 +42,6 @@
 using namespace bson;
 
 namespace mongo {
-    void stackCheck(const char *);
     namespace dbtests {
         extern unsigned perfHist;
     }
@@ -196,9 +195,7 @@ namespace PerfTests {
         // return name of it
         virtual string timed2(DBClientBase&) { return ""; }
 
-        virtual void post() {
-            stackCheck("dbtests perftests");
-        }
+        virtual void post() { }
 
         virtual string name() = 0;
 

src/mongo/unittest/unittest.cpp

@@ -28,8 +28,6 @@
 
 namespace mongo {
 
-    void stackCheck(const char *);
-
     namespace unittest {
 
         namespace {
@@ -183,8 +181,6 @@ namespace mongo {
 
                 log() << "going to run suite: " << name << std::endl;
                 results.push_back( s->run( filter ) );
-
-                stackCheck("dbtests");
             }
 
             Logstream::get().flush();