Missing `-lpthread` causes gcc test failure.

[chaoren]

Summary

-lpthread was removed for g++ -std=c++11 on Linux due to llvm.org/pr21553,
but the original issue doesn't seem to be reproducible anymore. Even if it were,
it had nothing to do with compiling inferiors.

[sivachandra]

LGTM if you think this is not going to trouble the builders.

test/functionalities/watchpoint/hello_watchlocation/TestWatchLocation.py

class HelloWatchLocationTestCase(TestBase):
     def test_hello_watchlocation_with_dsym(self):
         """Test watching a location with '-s size' option."""
         self.buildDsym(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         self.hello_watchlocation()
 
     @expectedFailureFreeBSD("llvm.org/pr18832")
     @dwarf_test
-    @expectedFailureGcc #xfail to get buildbot green, test failed with gcc4.8.2
     def test_hello_watchlocation_with_dwarf(self):
         """Test watching a location with '-s size' option."""
         self.buildDwarf(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         self.hello_watchlocation()
 
     def setUp(self):
         # Call super's setUp().

test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py

class WatchLocationUsingWatchpointSetTestCase(TestBase):
     def test_watchlocation_with_dsym_using_watchpoint_set(self):
         """Test watching a location with 'watchpoint set expression -w write -s size' option."""
         self.buildDsym(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         self.watchlocation_using_watchpoint_set()
 
     @expectedFailureFreeBSD('llvm.org/pr18832')
     @dwarf_test
-    @expectedFailureGcc #xfail to get buildbot green, test failed with gcc4.8.2
     def test_watchlocation_with_dwarf_using_watchpoint_set(self):
         """Test watching a location with 'watchpoint set expression -w write -s size' option."""
         self.buildDwarf(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         self.watchlocation_using_watchpoint_set()
 
     def setUp(self):
         # Call super's setUp().

test/functionalities/watchpoint/watchpoint_set_command/TestWatchpointSetErrorCases.py

 """
 Test error cases for the 'watchpoint set' command to make sure it errors out when necessary.
 """
 
 import os, time
 import unittest2
 import lldb
 from lldbtest import *
 import lldbutil
 
 class WatchpointSetErrorTestCase(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
 
     @expectedFailureFreeBSD('llvm.org/pr18832')
-    @expectedFailureGcc #xfail to get buildbot green, test failed with gcc4.8.2
     def test_error_cases_with_watchpoint_set(self):
         """Test error cases with the 'watchpoint set' command."""
         self.buildDwarf(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         self.error_cases_with_watchpoint_set()
 
     def setUp(self):
         # Call super's setUp().

test/make/Makefile.rules

 ifeq "$(CC)" "cc"
   CC = clang
 endif
 
 #----------------------------------------------------------------------
 # ARCHFLAG is the flag used to tell the compiler which architecture
 # to compile for. The default is the flag that clang accepts.
 #----------------------------------------------------------------------
-ARCHFLAG ?= -arch 
+ARCHFLAG ?= -arch
 
 #----------------------------------------------------------------------
 # Change any build/tool options needed
 #----------------------------------------------------------------------
 ifeq "$(OS)" "Darwin"
   DS := $(shell xcrun -find -toolchain default dsymutil)
   DSFLAGS =
   DSYM = $(EXE).dSYM

 CFLAGS_NO_DEBUG = -O0 $(ARCHFLAG)$(ARCH) $(FRAMEWORK_INCLUDES) $(CFLAGS_EXTRAS)
 
 CXXFLAGS += -std=c++11
 CXXFLAGS += $(CFLAGS)
 LD = $(CC)
 LDFLAGS ?= $(CFLAGS)
 LDFLAGS += $(LD_EXTRAS)
 ifeq (,$(filter $(OS), Windows_NT Android))
-    ifeq "$(ENABLE_THREADS)" "YES"
-        LDFLAGS += -lpthread
-    else
-        ifeq "$(ENABLE_STD_THREADS)" "YES"
-            # with the specific combination of Linux, g++, std=c++11, adding the 
-            # linker flag -lpthread, will cause a program to hang when a std::conditional_variable
-            # is used in a program that links lldb (see bugzilla 21553)
-            ifeq "$(OS)" "Linux"
-                ifeq (,$(findstring gcc,$(CC))) 
-                    # Linux, but not gcc
-                    LDFLAGS += -lpthread
-                endif
-            else
-                LDFLAGS += -lpthread
-            endif
-        endif
-    endif
+  ifneq (,$(filter YES,$(ENABLE_THREADS) $(ENABLE_STD_THREADS)))
+    LDFLAGS += -lpthread
+  endif
 endif
 OBJECTS =
 EXE ?= a.out
 
 ifneq "$(DYLIB_NAME)" ""
   ifeq "$(OS)" "Darwin"
     DYLIB_FILENAME = lib$(DYLIB_NAME).dylib
-  else ifeq "$(OS)" "Windows_NT"
-    DYLIB_FILENAME = $(DYLIB_NAME).dll
+  else ifeq "$(OS)" "Windows_NT"
+    DYLIB_FILENAME = $(DYLIB_NAME).dll
   else
     DYLIB_FILENAME = lib$(DYLIB_NAME).so
   endif
 endif
 
 # Function that returns the counterpart C++ compiler, given $(CC) as arg.
 cxx_compiler_notdir = $(if $(findstring clang,$(1)), \
                            $(subst clang,clang++,$(1)), \

 # Usage: make print-CC print-CXX print-LD
 #----------------------------------------------------------------------
 print-%:
   @echo '$*=$($*)'
   @echo '  origin = $(origin $*)'
   @echo '  flavor = $(flavor $*)'
   @echo '   value = $(value  $*)'
 
-␌
 ### Local Variables: ###
 ### mode:makefile ###
 ### End: ###