BaseTools: introduce !error statement

The DSC and FDF file can use `!error` statement. The argument of this
statement is an error message, it causes build tool to stop at the
location where the statement is encountered and error message following
the `!error` statement is output as a message.

Fixes: https://bugzilla.tianocore.org/show_bug.cgi?id=701
Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

BaseTools/Source/Python/GenFds/FdfParser.py

@@ -1361,6 +1361,7 @@ class FdfParser:
 
         try:
             self.Preprocess()
+            self.__GetError()
             #
             # Keep processing sections of the FDF until no new sections or a syntax error is found
             #
@@ -1441,6 +1442,17 @@ class FdfParser:
 
         return False
 
+    ##__GetError() method
+    def __GetError(self):
+        #save the Current information
+        CurrentLine = self.CurrentLineNumber
+        CurrentOffset = self.CurrentOffsetWithinLine
+        while self.__GetNextToken():
+            if self.__Token == TAB_ERROR:
+                EdkLogger.error('FdfParser', ERROR_STATEMENT, self.__CurrentLine().replace(TAB_ERROR, '', 1), File=self.FileName, Line=self.CurrentLineNumber)
+        self.CurrentLineNumber = CurrentLine
+        self.CurrentOffsetWithinLine = CurrentOffset
+
     ## __GetFd() method
     #
     #   Get FD section contents and store its data into FD dictionary of self.Profile