[GRASS-git] [OSGeo/grass] c04f03: Fix -Wunused-result compiler warnings (#2166)

[Nicklas Larsson]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: c04f03ae0a1aa0300fc130c3ed30e33d12bfc271
      https://github.com/OSGeo/grass/commit/c04f03ae0a1aa0300fc130c3ed30e33d12bfc271
  Author: Nicklas Larsson <n_larsson at yahoo.com>
  Date:   2022-11-06 (Sun, 06 Nov 2022)

  Changed paths:
    M display/d.mon/start.c
    M general/g.proj/input.c
    M general/g.rename/main.c
    M lib/bitmap/bitmap.c
    M lib/cairodriver/read_bmp.c
    M lib/db/dbmi_driver/d_error.c
    M lib/gis/error.c
    M lib/gis/writ_zeros.c
    M lib/rst/interp_float/output2d.c
    M lib/rst/interp_float/resout2d.c
    M lib/vector/Vlib/break_polygons.c
    M ps/ps.map/eps.c
    M raster/r.fill.dir/dopolys.c
    M raster/r.fill.dir/filldir.c
    M raster/r.fill.dir/main.c
    M raster/r.fill.dir/ppupdate.c
    M raster/r.fill.dir/resolve.c
    M raster/r.fill.dir/wtrshed.c
    M raster/r.grow.distance/main.c
    M raster/r.in.ascii/gethead.c
    M raster/r.in.ascii/main.c
    M raster/r.in.bin/main.c
    M raster/r.in.gridatb/file_io.c
    M raster/r.in.mat/main.c
    M raster/r.param.scale/disp_matrix.c
    M raster/r.topmodel/file_io.c
    M vector/v.vol.rst/user1.c

  Log Message:
  -----------
  Fix -Wunused-result compiler warnings (#2166)

* -Wunused-result compiler warnings addressed in following parts:

GRASS Modules:

d.mon
g.proj
g.rename
ps.map
r.fill.dir
r.grow.distance
r.in.ascii
r.in.bin
r.in.gridatb
r.in.mat
r.param.scale
r.topmodel
v.vol.rst

GRASS Library parts:

lib/bitmap
lib/cairodriver
lib/db/dbmi_driver
lib/gis
lib/rst/interp_float
lib/vector/Vlib/

Almost exclusively these fixes are file I/O related, handling return
values from calls with read()/fread(), write()/fwrite(), fgets(),
fscanf(), getcwd().

In addition, potential overflow of int before it is converted to size_t
was avoided in r.in.mat/main.c