[makefile] update support for WSL, remove gcc version detect

Signed-off-by: R4SAS <r4sas@i2pmail.org>

Makefile

@@ -4,7 +4,7 @@ SYS := $(shell $(CXX) -dumpmachine)
 
 ifneq (, $(findstring darwin, $(SYS)))
 	SHARED_SUFFIX = dylib
-else ifneq (, $(findstring mingw, $(SYS))$(findstring cygwin, $(SYS)))
+else ifneq (, $(findstring mingw, $(SYS))$(findstring windows-gnu, $(SYS))$(findstring cygwin, $(SYS)))
 	SHARED_SUFFIX = dll
 else
 	SHARED_SUFFIX = so
@@ -60,7 +60,7 @@ else ifneq (, $(findstring linux, $(SYS))$(findstring gnu, $(SYS)))
 else ifneq (, $(findstring freebsd, $(SYS))$(findstring openbsd, $(SYS)))
 	DAEMON_SRC += $(DAEMON_SRC_DIR)/UnixDaemon.cpp
 	include Makefile.bsd
-else ifneq (, $(findstring mingw, $(SYS))$(findstring cygwin, $(SYS)))
+else ifneq (, $(findstring mingw, $(SYS))$(findstring windows-gnu, $(SYS))$(findstring cygwin, $(SYS)))
 	DAEMON_SRC += Win32/DaemonWin32.cpp Win32/Win32App.cpp Win32/Win32Service.cpp Win32/Win32NetState.cpp
 	include Makefile.mingw
 else # not supported

Makefile.mingw

@@ -3,19 +3,11 @@ USE_WIN32_APP := yes
 
 WINDRES = windres
 
-CXXFLAGS := $(CXX_DEBUG) -DWIN32_LEAN_AND_MEAN -fPIC -msse
+CXXFLAGS := $(CXX_DEBUG) -fPIC -msse
 INCFLAGS = -I$(DAEMON_SRC_DIR) -IWin32
 LDFLAGS := ${LD_DEBUG} -static
 
-# detect proper flag for c++11 support by compilers
-CXXVER := $(shell $(CXX) -dumpversion)
-ifeq ($(shell expr match ${CXXVER} "[4]\.[7-9]\|4\.1[0-9]\|[5-6]"),4) # gcc 4.7 - 6
-	NEEDED_CXXFLAGS += -std=c++11
-else ifeq ($(shell expr match ${CXXVER} "[1,7-9]"),1) # gcc >= 7
-	NEEDED_CXXFLAGS += -std=c++17
-else # not supported
-$(error Compiler too old)
-endif
+NEEDED_CXXFLAGS += -std=c++17 -DWIN32_LEAN_AND_MEAN
 
 # Boost libraries suffix
 BOOST_SUFFIX = -mt