Building libsdl fails for lack of Xext.h

[jtbr]

Linux mint 21.1 (Ubuntu 20.04)

Workaround is to
# apt install libxext-dev

Building gives the following:

building libsdl - version 2.26.3
=======================
SDL2-2.26.3.tar.gz has already downloaded.
Extracted SDL2-2.26.3.tar.gz
$ ./configure --prefix=/home/briggsjt/WORKING/ffmpeg-build-script/workspace --disable-shared --enable-static
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking how to print strings... printf
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checking whether the C compiler works... yes
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checking whether the compiler supports GNU C++... yes
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checking how to run the C++ preprocessor... g++ -E
checking for ld used by g++... /usr/bin/ld -m elf_x86_64
checking if the linker (/usr/bin/ld -m elf_x86_64) is GNU ld... yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking for g++ option to produce PIC... -fPIC -DPIC
checking if g++ PIC flag -fPIC -DPIC works... yes
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checking if g++ supports -c -o file.o... yes
checking if g++ supports -c -o file.o... (cached) yes
checking whether the g++ linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes
checking dynamic linker characteristics... (cached) GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
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checking whether make sets $(MAKE)... yes
checking for pkg-config... /home/briggsjt/WORKING/ffmpeg-build-script/workspace/bin/pkg-config
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checking for ALSA CFLAGS... 
checking for ALSA LDFLAGS...  -lasound -lm -ldl -lpthread
checking for libasound headers version >= 1.0.11... not present.
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checking for X... libraries , headers 
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checking for connect... yes
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checking for shmat... yes
checking for IceConnectionNumber in -lICE... yes
checking for X11/extensions/Xext.h... no
configure: error: 
*** Missing Xext.h, maybe you need to install the libxext-dev package?

[jtbr]

Issue #171 mentions this as well for Ubuntu 22.04