recognize compiler version without gexpr

Makefile.bsd

@@ -11,10 +11,10 @@ LDLIBS = -lcrypto -lssl -lz -lpthread -lboost_system -lboost_program_options
 ## (e.g. -fstack-protector-strong -Wformat -Werror=format-security), we do not want to remove
 ## -std=c++11. If you want to remove this variable please do so in a way that allows setting
 ## custom FLAGS to work at build-time.
-CXXVER := $(shell $(CXX) -dumpversion)
-ifeq (${CXXVER}, "4.2.1") # older clang always returned 4.2.1
+CXXVER := $(shell $(CXX) -dumpversion|cut -c 1-2)
+ifeq (${CXXVER}, "4.") # older clang always returned 4.2.1
 	$(error Compiler too old)
-else ifeq ($(shell gexpr match ${CXXVER} "1[6-9]"),2) # clang 16 - 19
+else ifeq (${CXXVER}, ${filter ${CXXVER},16 17 18 19})  # clang 16 - 19
 	NEEDED_CXXFLAGS = -std=c++20
 else
 	NEEDED_CXXFLAGS = -std=c++17