revert the --enable-clang option
revert the --enable-clang option

This should be completely equivalent to ./autogen.sh CC=clang CXX=clang++ ,
which is the normal way to pass any compiler to configure, so this is needless
duplication.
This reverts commits 1a843cc54dd6a08fa5fccb4314c025d432e46ad1 and
02ed2608199f2adc466849d0f4864213ad07c445 .

Change-Id: Ib02ab84a7b84fe4797dca0f62aa5049c1be55302

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core