Add the module wcswidth from the GNU Portability Library

lib/.gitignore

@@ -114,6 +114,8 @@ wcsdup.c
 wcsrtombs-impl.h
 wcsrtombs-state.c
 wcsrtombs.c
+wcswidth-impl.h
+wcswidth.c
 wctob.c
 wctomb-impl.h
 wctomb.c

m4/.gitignore

@@ -112,6 +112,7 @@ wchar_t.m4
 wcrtomb.m4
 wcsdup.m4
 wcsrtombs.m4
+wcswidth.m4
 wctob.m4
 wctomb.m4
 wctype_h.m4

m4/gnulib-cache.m4

@@ -15,7 +15,7 @@
 
 
 # Specification in the form of a command-line invocation:
-#   gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-conditional-dependencies --no-libtool --macro-prefix=gl assert btowc config-h ctype fprintf-posix getopt-gnu gettext gettext-h gettimeofday langinfo locale mbrtowc mbsrtowcs printf-posix sigaction signal snprintf-posix stat stdarg stdbool stdio strdup-posix striconv string strncat strstr sys_stat sys_time unistd vfprintf-posix vsnprintf-posix wchar wcrtomb wcsdup wcsrtombs wctob wctype-h wcwidth
+#   gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --no-conditional-dependencies --no-libtool --macro-prefix=gl assert btowc config-h ctype fprintf-posix getopt-gnu gettext gettext-h gettimeofday langinfo locale mbrtowc mbsrtowcs printf-posix sigaction signal snprintf-posix stat stdarg stdbool stdio strdup-posix striconv string strncat strstr sys_stat sys_time unistd vfprintf-posix vsnprintf-posix wchar wcrtomb wcsdup wcsrtombs wcswidth wctob wctype-h wcwidth
 
 # Specification in the form of a few gnulib-tool.m4 macro invocations:
 gl_LOCAL_DIR([])
@@ -55,6 +55,7 @@ gl_MODULES([
   wcrtomb
   wcsdup
   wcsrtombs
+  wcswidth
   wctob
   wctype-h
   wcwidth