[webkit-dev] how to build webkit with qt4

[sonic]

I try to build webkit on Linux.
To build with qt4, I follow the instruction from webkit.org, using the
following command:
QTDIR=/usr/shared/qt4 WebKitTools/Script/build-webkit

but I got the following errors:
make[1]: Entering directory `/home/jcai/webkitnew/WebKitBuild/Release/WebCore'
echo \"#include <string.h>\" >
/home/jcai/webkitnew/WebKitBuild/Release/WebCore/tmp/DocTypeStrings.cpp
&& gperf -CEot -L ANSI-C -k \'*\' -N findDoctypeEntry -F
,PubIDInfo::eAlmostStandards,PubIDInfo::eAlmostStandards <
/home/jcai/webkitnew/WebCore/html/DocTypeStrings.gperf >>
/home/jcai/webkitnew/WebKitBuild/Release/WebCore/tmp/DocTypeStrings.cpp
/bin/sh: string.h: No such file or directory
make[1]: *** [/home/jcai/webkitnew/WebKitBuild/Release/WebCore/tmp/DocTypeStrings.cpp]
Error 1
make[1]: Leaving directory `/home/jcai/webkitnew/WebKitBuild/Release/WebCore'
make: *** [sub-WebCore-make_default-ordered] Error 2

can someone tell me why?

-- 
Cai Jian