BASIC : useless std::unique_ptr initialisation

Change-Id: I841cbb2bad3af5f6f6212962d7f15436d5e7bead
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/102105
Tested-by: Jenkins
Reviewed-by: Arnaud Versini <arnaud.versini@libreoffice.org>

basic/source/comp/buffer.cxx

@@ -33,7 +33,6 @@ SbiBuffer::SbiBuffer( SbiParser* p, short n )
     pParser = p;
     n = ( (n + 15 ) / 16 ) * 16;
     if( !n ) n = 16;
-    pBuf  = nullptr;
     pCur  = nullptr;
     nInc  = n;
     nSize =