icecast: build error due to libxml2 include

Maintainer: @andrenarchy, @thess
Environment: Netgear R9000 ARMv7 Processor rev 4 (v7l)

make V=s package/icecast/compile
...
make[6]: Entering directory '/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4/src'
arm-openwrt-linux-muslgnueabi-gcc -DHAVE_CONFIG_H -I. -I..  -Wall -ffast-math -fsigned-char -I/home/egorenar/Repositories/openwrt-rel/staging_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/usr/include -I/home/egorenar/Repositories/openwrt-rel/staging_dir/toolchain-arm_cortex-a15+neon-vfpv4_gcc-11.3.0_musl_eabi/usr/include -I/home/egorenar/Repositories/openwrt-rel/staging_dir/toolchain-arm_cortex-a15+neon-vfpv4_gcc-11.3.0_musl_eabi/include/fortify -I/home/egorenar/Repositories/openwrt-rel/staging_dir/toolchain-arm_cortex-a15+neon-vfpv4_gcc-11.3.0_musl_eabi/include     -Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -mfloat-abi=hard -fmacro-prefix-map=/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4=icecast-2.4.4 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro    -MT cfgfile.o -MD -MP -MF .deps/cfgfile.Tpo -c -o cfgfile.o cfgfile.c
cfgfile.c:26:10: fatal error: libxml/xmlmemory.h: No such file or directory
   26 | #include <libxml/xmlmemory.h>
      |          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[6]: *** [Makefile:545: cfgfile.o] Error 1
make[6]: Leaving directory '/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4/src'
make[5]: *** [Makefile:578: all-recursive] Error 1
make[5]: Leaving directory '/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4/src'
make[4]: *** [Makefile:495: all-recursive] Error 1
make[4]: Leaving directory '/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4'
make[3]: *** [Makefile:406: all] Error 2
make[3]: Leaving directory '/home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4'
make[2]: *** [Makefile:84: /home/egorenar/Repositories/openwrt-rel/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/icecast-2.4.4/.built] Error 2
make[2]: Leaving directory '/home/egorenar/Repositories/openwrt-rel/feeds/packages/multimedia/icecast'
time: package/feeds/packages/icecast/compile#0.13#0.08#0.21
    ERROR: package/feeds/packages/icecast failed to build.
make[1]: *** [package/Makefile:116: package/feeds/packages/icecast/compile] Error 1
make[1]: Leaving directory '/home/egorenar/Repositories/openwrt-rel'
make: *** [/home/egorenar/Repositories/openwrt-rel/include/toplevel.mk:231: package/icecast/compile] Error 2

My fix:

TARGET_CFLAGS+= \
	-I$(STAGING_DIR)/usr/include/libxml2

Start at the icecast package build entry under feeds/packages/multimedia/icecast and inspect the compile command that builds src/cfgfile.c. Check how the libxml2 headers are exposed to the target compiler, then rerun make V=s package/icecast/compile; done means the package compiles without the missing libxml/xmlmemory.h error.