Add yet another module from the GNU Portability Library: btowc

lib/.gitignore

@@ -1,6 +1,7 @@
 Makefile.am
 alloca.in.h
 asnprintf.c
+btowc.c
 c-ctype.c
 c-ctype.h
 c-strcase.h
@@ -52,6 +53,8 @@ mbsinit.c
 mbsrtowcs-impl.h
 mbsrtowcs-state.c
 mbsrtowcs.c
+mbtowc-impl.h
+mbtowc.c
 memchr.c
 memchr.valgrind
 printf-args.c

m4/.gitignore

@@ -2,6 +2,7 @@
 alloca.m4
 asm-underscore.m4
 assert.m4
+btowc.m4
 codeset.m4
 config-h.m4
 configmake.m4
@@ -62,6 +63,7 @@ mbrtowc.m4
 mbsinit.m4
 mbsrtowcs.m4
 mbstate_t.m4
+mbtowc.m4
 memchr.m4
 mmap-anon.m4
 multiarch.m4

m4/gnulib-cache.m4

@@ -15,12 +15,13 @@
 
 
 # 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 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 wcsrtombs 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 wcsrtombs wctype-h wcwidth
 
 # Specification in the form of a few gnulib-tool.m4 macro invocations:
 gl_LOCAL_DIR([])
 gl_MODULES([
   assert
+  btowc
   config-h
   ctype
   fprintf-posix