Same as D25376.
If this transition to just a makefile will not be accepted an alternative patch is needed to build pructl @head.
Something like:

• rpaulo-pructl-ef9fa544e6a3/CMakeLists.txt 2015-02-22 20:46:15.000000000 +0000

+++ pructl/CMakeLists.txt 2020-06-20 20:35:47.404949000 +0000
@@ -6,7 +6,8 @@
find_library(libpru NAMES pru PATHS /usr/local/lib ${CMAKE_SOURCE_DIR}/../libpru/build)
find_library(libedit NAMES edit)
find_library(libutil NAMES util)
-target_link_libraries(pructl ${libpru})
-target_link_libraries(prudbg ${libpru} ${libedit} ${libutil})
-set(CMAKE_C_FLAGS "-Weverything -Werror")
+find_library(libpthread NAMES pthread)
+target_link_libraries(pructl ${libpru} ${libpthread})
+target_link_libraries(prudbg ${libpru} ${libedit} ${libutil} ${libpthread})
+set(CMAKE_C_FLAGS "-Werror")
install(TARGETS pructl prudbg DESTINATION sbin)