textstyle.h missing when building bison from current head

[Anthony Heading]

Hi,

I'm getting the error below when trying to build bison HEAD from github,
with a vanilla sequence of 'bootstrap', 'configure', 'make'.    The latest
v3.8.2 bison release builds fine as I think it precedes gnulib updates in
December.

% make
  [...]
  GEN      lib/iconv.h
  GEN      lib/inttypes.h
make: *** No rule to make target 'textstyle.h', needed by 'all'.  Stop.

Some relevant vars in config.log; I think the path should maybe be
lib/textstyle.h instead

% grep TEXTSTYLE_H config.log
config.log:GL_GENERATE_TEXTSTYLE_H_FALSE='#'
config.log:GL_GENERATE_TEXTSTYLE_H_TRUE=''
config.log:TEXTSTYLE_H='textstyle.h'

I think what may be happening is recent gnulib changes moves generation of
textstyle.h earlier (the code appears in configure twice), but the first
invocation comes *before* gl_source_base_prefix has been set to 'lib'.

% grep 'TEXTSTYLE_H=\|gl_source_base_prefix=' configure                         
                                                                 ─╯
    GL_GENERATE_TEXTSTYLE_H=false
    GL_GENERATE_TEXTSTYLE_H=true
    false) TEXTSTYLE_H='' ;;
        TEXTSTYLE_H="${gl_source_base_prefix}textstyle.h"
  gl_source_base_prefix='$(top_build_prefix)lib/'
    GL_GENERATE_TEXTSTYLE_H=false
    false) TEXTSTYLE_H='' ;;
        TEXTSTYLE_H="${gl_source_base_prefix}textstyle.h"
  gl_source_base_prefix=