correct static lib extension on *nix

install_libfilteraudio.sh

@@ -16,11 +16,13 @@ fi
 
 WINDOWS_VERSION=$(cmd.exe /c ver 2>/dev/null | grep "Microsoft Windows")
 if [ ! -z "$WINDOWS_VERSION" ]; then
-  EXT=dll
+  EXT="dll"
   BIN_DIR="$2/bin/"
+  STATIC_EXT="$EXT.a"
 else
   BIN_DIR=$LIB_DIR
-  EXT=so
+  EXT="so"
+  STATIC_EXT="a"
 fi
 
 echo "Cloning filter_audio from GitHub.com"
@@ -31,7 +33,7 @@ cd $SOURCE_DIR
 gcc -c -fPIC filter_audio.c aec/*.c agc/*.c ns/*.c other/*.c  -lm -lpthread
 
 echo "Creating shared object file"
-gcc *.o -shared -o libfilteraudio.$EXT -Wl,--out-implib,libfilteraudio.$EXT.a
+gcc *.o -shared -o libfilteraudio.$EXT -Wl,--out-implib,libfilteraudio.$STATIC_EXT
 
 echo "Cleaning up"
 rm *.o
@@ -41,9 +43,9 @@ muhcmd="cp libfilteraudio.$EXT $BIN_DIR"
 echo "Installing libfilteraudio.so with $muhcmd"
 $muhcmd
 
-muhcmd="cp libfilteraudio.$EXT.a $LIB_DIR"
+muhcmd="cp libfilteraudio.$STATIC_EXT $LIB_DIR"
 [ -z "$2" ] && muhcmd="sudo $muhcmd"
-echo "Installing libfilteraudio.$EXT.a with $muhcmd"
+echo "Installing libfilteraudio.$STATIC_EXT with $muhcmd"
 $muhcmd
 
 muhcmd="cp *.h $INCLUDE_DIR"