cmake: fix Python requirement
Perl is no longer needed.
Python must be version 3. Version 2 is not suitable.
The variable is PYTHONINTERP_FOUND, not PYTHON_FOUND.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7f2b502..4350d4e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -51,9 +51,9 @@
"${CTR_DRBG_128_BIT_KEY_WARN_L3}"
"${WARNING_BORDER}")
-find_package(PythonInterp)
-find_package(Perl)
-if(PYTHON_FOUND)
+# Python 3 is only needed here to check for configuration warnings.
+find_package(PythonInterp 3)
+if(PYTHONINTERP_FOUND)
# If 128-bit keys are configured for CTR_DRBG, display an appropriate warning
execute_process(COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/config.py -f ${CMAKE_CURRENT_SOURCE_DIR}/include/mbedtls/config.h get MBEDTLS_CTR_DRBG_USE_128_BIT_KEY