Fix .bat file comments

build_windows.bat

@@ -1,7 +1,7 @@
-# Build using Visual Studio 2019 on Windows
-# Additional tools needed: git, cmake and ninja
+REM Build using Visual Studio 2019 on Windows
+REM Additional tools needed: git, cmake and ninja
 
-# Build zlib
+REM Build zlib
 git clone https://github.com/madler/zlib
 cd zlib
 mkdir build
@@ -10,7 +10,7 @@ cmake -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DMSVC_TOOLSET_VERSION=190 -DCMAKE_BU
 ninja install
 cd ../../
 
-# Build libpng
+REM Build libpng
 git clone https://github.com/glennrp/libpng
 cd libpng
 mkdir build
@@ -19,7 +19,7 @@ cmake -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DMSVC_TOOLSET_VERSION=190 -DCMAKE_BU
 ninja install
 cd ../..
 
-# Build libsndfile - Could build Vorbis, FLAC and Opus first for extra support
+REM Build libsndfile - Could build Vorbis, FLAC and Opus first for extra support
 git clone https://github.com/libsndfile/libsndfile.git
 cd libsndfile
 mkdir build
@@ -28,7 +28,7 @@ cmake -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DMSVC_TOOLSET_VERSION=190 -DCMAKE_BU
 ninja install
 cd ../..
 
-# Build aptdec
+REM Build aptdec
 mkdir winbuild
 cd winbuild
 cmake -G Ninja -DCMAKE_C_COMPILER="cl.exe" -DMSVC_TOOLSET_VERSION=190 -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=../winpath ..