libcpufeatures in only used in libwebp for NEON,
and all Termux's supported ARM devices support NEON
(Android 5.0+ requires NEON: https://developer.android.com/ndk/guides/cpu-arm-neon)
and the NEON support is already successfully detected at configure-time separately from this:
-- Performing Test WEBP_HAVE_FLAG_NEON - Success

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -181,7 +181,7 @@ endif()
 
 # ##############################################################################
 # Android only.
-if(ANDROID)
+if(FALSE)
   include_directories(${ANDROID_NDK}/sources/android/cpufeatures)
   add_library(cpufeatures-webp STATIC
               ${ANDROID_NDK}/sources/android/cpufeatures/cpu-features.c)