appveyor.(cmd|sh): Add ENABLE_NLS to the options list.

[librptext] conversion.cpp: #include <cstring> to fix breakage if
-DENABLE_NLS=OFF. (i18n.h includes gettext.h, which includes string.h.)

appveyor.cmd

@@ -7,7 +7,7 @@ if "%1" == "OFF" (
 ) else (
 	set OPTEN=ON
 )
-set "OPTFEAT=-DENABLE_EXTRA_SECURITY=%OPTEN% -DENABLE_JPEG=%OPTEN% -DENABLE_XML=%OPTEN% -DENABLE_DECRYPTION=%OPTEN% -DENABLE_UNICE68=%OPTEN% -DENABLE_LIBMSPACK=%OPTEN% -DENABLE_PVRTC=%OPTEN% -DENABLE_ZSTD=%OPTEN% -DENABLE_LZ4=%OPTEN% -DENABLE_LZO=%OPTEN%"
+set "OPTFEAT=-DENABLE_EXTRA_SECURITY=%OPTEN% -DENABLE_JPEG=%OPTEN% -DENABLE_XML=%OPTEN% -DENABLE_DECRYPTION=%OPTEN% -DENABLE_UNICE68=%OPTEN% -DENABLE_LIBMSPACK=%OPTEN% -DENABLE_PVRTC=%OPTEN% -DENABLE_ZSTD=%OPTEN% -DENABLE_LZ4=%OPTEN% -DENABLE_LZO=%OPTEN% -DENABLE_NLS=%OPTEN%"
 
 :: FIXME: Get multiple compilers working again.
 :: For now, it's MSVC only for the Windows build.

appveyor.sh

@@ -9,7 +9,7 @@ else
 	export OPTEN=ON
 fi
 
-OPTFEAT="-DENABLE_EXTRA_SECURITY=${OPTEN} -DENABLE_JPEG=${OPTEN} -DENABLE_XML=${OPTEN} -DENABLE_DECRYPTION=${OPTEN} -DENABLE_UNICE68=${OPTEN} -DENABLE_LIBMSPACK=${OPTEN} -DENABLE_PVRTC=${OPTEN} -DENABLE_ZSTD=${OPTEN} -DENABLE_LZ4=${OPTEN} -DENABLE_LZO=${OPTEN}"
+OPTFEAT="-DENABLE_EXTRA_SECURITY=${OPTEN} -DENABLE_JPEG=${OPTEN} -DENABLE_XML=${OPTEN} -DENABLE_DECRYPTION=${OPTEN} -DENABLE_UNICE68=${OPTEN} -DENABLE_LIBMSPACK=${OPTEN} -DENABLE_PVRTC=${OPTEN} -DENABLE_ZSTD=${OPTEN} -DENABLE_LZ4=${OPTEN} -DENABLE_LZO=${OPTEN} -DENABLE_NLS=${OPTEN}"
 
 mkdir build || true
 cd build

src/librptext/conversion.cpp

@@ -24,6 +24,7 @@
 
 // C includes (C++ namespace)
 #include <cassert>
+#include <cstring>
 #include <cwctype>
 
 // for strnlen() if it's not available in <string.h>