Error building LO - "strlen was not declared in this scope" on fresh Ubuntu 15.04 install

Hi there,
after
 several minutes of compilation I got the following error(s). Any ideas?
[Manual dirty solutions like insert the related #include macros did not
work]

// beginning error message from make
[SOMEPATH]/include/rtl/ustring.hxx:188:27: error: ‘strlen’ was not declared
in this scope
In file included from [SOMEPATH]/include/xmlreader/pad.hxx:27:0,
                 from [SOMEPATH]/include/xmlreader/xmlreader.hxx:35,
                 from [SOMEPATH]/include/vcl/builder.hxx:19,
                 from [SOMEPATH]/include/vcl/dialog.hxx:25,
                 from [SOMEPATH]/editeng/source/editeng/editdbg.cxx:22:
[SOMEPATH]/include/rtl/strbuf.hxx: In instantiation of ‘typename
rtl::internal::ConstCharArrayDetector<T, rtl::OStringBuffer&>::Type
rtl::OStringBuffer::append(T&) [with T = const char [12]; typename
rtl::internal::ConstCharArrayDetector<T, rtl::OStringBuffer&>::Type =
rtl::OStringBuffer&]’:
[SOMEPATH]/editeng/source/editeng/editdbg.cxx:70:41:   required from here
[SOMEPATH]/include/rtl/strbuf.hxx:477:27: error: ‘strlen’ was not declared
in this scope
         assert( strlen( literal ) == internal::ConstCharArrayDetector< T
> ::size - 1 );

// end errors

Matteo