[Patch] BaseTools: Fix the Windows GCC Build Failure with too long path

[Yonghong Zhu <yonghong.zhu@intel.com>]

When path is too long, build tool will wrap them into resp.txt, then call
gcc @resp.txt. It will cause windows GCC build failure, because resp.txt
still uses windows directory separator \. This patch change the \ to /.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
---
 BaseTools/Source/Python/AutoGen/GenMake.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/BaseTools/Source/Python/AutoGen/GenMake.py b/BaseTools/Source/Python/AutoGen/GenMake.py
index c8c5fc5..51c5238 100644
--- a/BaseTools/Source/Python/AutoGen/GenMake.py
+++ b/BaseTools/Source/Python/AutoGen/GenMake.py
@@ -766,11 +766,15 @@ cleanlib:
                                 if (Value.find(MacroName) != -1):
                                     Value = Value.replace(MacroName, self._AutoGenObject.Macros[macro])
                                     break
                             else:
                                 break
-                        RespDict[Key] = Value
+
+                        if self._AutoGenObject.ToolChainFamily == 'GCC':
+                            RespDict[Key] = Value.replace('\\', '/')
+                        else:
+                            RespDict[Key] = Value
                         for Target in BuildTargets:
                             for i, SingleCommand in enumerate(BuildTargets[Target].Commands):
                                 if FlagDict[Flag]['Macro'] in SingleCommand:
                                     BuildTargets[Target].Commands[i] = SingleCommand.replace('$(INC)','').replace(FlagDict[Flag]['Macro'], RespMacro)
         return RespDict
-- 
2.6.1.windows.1