Probably minor bug

[Chris Moller]

    Shape.hh: In member function 'Shape
        Shape::insert_axis(Axis, ShapeItem) const':
      Shape.hh:69:46: error: ''target_mem_ref' not supported by
        dump_expr<_expression_ error>' may be used uninitialized in
        this function [-Werror=maybe-uninitialized]
         69 |      loop(r, MAX_RANK)   rho[r] = other.rho[r];
            |                                   ~~~~~~~~~~~^
      
      Just to finish the build, I patched around the bug by editing out
      the Wall and the Werror in the Makefile, so:
      
      [moller@hpbox]~tinkering/gnuapl/trunk% apl
      -v                                                                      
      10:47:53
      BUILDTAG:
      ---------
          Project:        GNU APL
          Version / SVN:  1.8 / 1210
          Build Date:     2019-12-19 17:09:01 UTC
          Build OS:       Linux 4.19.3-200.fc28.x86_64 x86_64
          config.status: 
'PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig:/usr/local/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/lib/pkgconfig'
          Archive SVN:    1161
      
      [moller@hpbox]~tinkering/gnuapl/trunk% gcc
      --version                                                               
      10:49:35
      gcc (GCC) 10.1.1 20200507 (Red Hat 10.1.1-1)
      
      [moller@hpbox]~tinkering/gnuapl/trunk% cat
      /etc/redhat-release                                                     
      10:51:45
      Fedora release 32 (Thirty Two)
      
      [moller@hpbox]~tinkering/gnuapl/trunk% uname
      -a                                                                    
      10:52:29
      Linux hpbox 5.6.19-300.fc32.x86_64 #1 SMP Wed Jun 17 16:10:48 UTC
      2020 x86_64 x86_64 x86_64 GNU/Linux