[doc] Building: minor updates to Debian/Ubuntu prerequisites

libtool-bin is something everyone already has installed so it slipped by unnoticed for more than half a decade.

SDL 1.2 support was removed 4 years ago: koreader/koreader-base#963

Fixes #10896.

doc/Building.md

@@ -22,8 +22,8 @@ Install the prerequisites using APT:
 
 ```
 sudo apt-get install build-essential git patch wget unzip \
-gettext autoconf automake cmake libtool nasm ragel luarocks lua5.1 libsdl2-dev \
-libssl-dev libffi-dev libsdl2-dev libc6-dev-i386 xutils-dev linux-libc-dev:i386 zlib1g:i386
+gettext autoconf automake cmake libtool libtool-bin nasm ragel luarocks lua5.1 libsdl2-dev \
+libssl-dev libffi-dev libc6-dev-i386 xutils-dev linux-libc-dev:i386 zlib1g:i386
 ```
 
 ### Fedora/Red Hat