BUILD: makefile: also drop DEBUG_CFLAGS

This one is often used as a gateway to inject regular CFLAGS, even though
not designed for this. It's now ignored, but any attempt at setting it
reports a warning suggesting to use CFLAGS or ARCH_FLAGS instead.

.github/matrix.py

@@ -117,7 +117,7 @@ def main(ref_name):
                 "TARGET": TARGET,
                 "CC": CC,
                 "FLAGS": [
-                    'DEBUG_CFLAGS="-DDEBUG_LIST"',
+                    'DEBUG="-DDEBUG_LIST"',
                     "USE_ZLIB=1",
                     "USE_OT=1",
                     "OT_INC=${HOME}/opt-ot/include",

INSTALL

@@ -657,11 +657,6 @@ section 4 about dependencies for more information on how to build with OpenSSL.
 HAProxy can compress HTTP responses to save bandwidth. Please see section 4
 about dependencies to see the available libraries and associated options.
 
-By default, the DEBUG_CFLAGS variable is set to '-g' to enable debug symbols.
-It is not wise to disable it on uncommon systems, because it's often the only
-way to get a usable core when you need one. Otherwise, you can set DEBUG to
-'-s' to strip the binary.
-
 If the ERR variable is set to any non-empty value other than "0", then -Werror
 will be added to the compiler so that any build warning will trigger an error.
 This is the recommended way to build when developing, and it is expected that
@@ -775,7 +770,7 @@ also run on 5.2 or earlier, you need to build with DEFINE="-D_MSGQSUPPORT",
 otherwise __fd_select() will be used while not being present in the libc, but
 this is easily addressed using the "aix52" target. If you get build errors
 because of strange symbols or section mismatches, simply remove -g from
-DEBUG_CFLAGS.
+ARCH_FLAGS.
 
 Building on AIX 7.2 works fine using the "aix72-gcc" TARGET. It adds two
 special CFLAGS to prevent the loading of AIX's xmem.h and var.h. This is done

Makefile

@@ -184,9 +184,16 @@ LD = $(CC)
 # other CFLAGS options if needed.
 OPT_CFLAGS = -O2
 
-#### Debug flags (typically "-g").
-# Those flags only feed CFLAGS so it is not mandatory to use this form.
-DEBUG_CFLAGS = -g
+#### No longer used
+DEBUG_CFLAGS =
+ifneq ($(DEBUG_CFLAGS),)
+$(warning Warning: DEBUG_CFLAGS was forced to "$(DEBUG_CFLAGS)" but is no     \
+  longer used and will be ignored. If you have ported this build setting from \
+  and older version, it is likely that you just want to pass these options    \
+  to the CFLAGS variable. If you are passing some debugging-related options   \
+  such as -g/-ggdb3/-pg etc, they can now be passed in ARCH_FLAGS at once for \
+  both the compilation and linking stages.)
+endif
 
 #### Add -Werror when set to non-empty
 ERR =
@@ -453,7 +460,6 @@ ifeq ($(TARGET),aix51)
   set_target_defaults = $(call default_opts, \
     USE_POLL USE_LIBCRYPT USE_OBSOLETE_LINKER)
   TARGET_CFLAGS   = -Dss_family=__ss_family -Dip6_hdr=ip6hdr -DSTEVENS_API -D_LINUX_SOURCE_COMPAT -Dunsetenv=my_unsetenv
-  DEBUG_CFLAGS    =
 endif
 
 # AIX 5.2
@@ -461,7 +467,6 @@ ifeq ($(TARGET),aix52)
   set_target_defaults = $(call default_opts, \
     USE_POLL USE_LIBCRYPT USE_OBSOLETE_LINKER)
   TARGET_CFLAGS   = -D_MSGQSUPPORT
-  DEBUG_CFLAGS    =
 endif
 
 # AIX 7.2 and above
@@ -490,7 +495,7 @@ $(set_target_defaults)
 # linking with it by default as it's not always available nor deployed
 # (especially on archs which do not need it).
 ifneq ($(USE_THREAD:0=),)
-  ifneq ($(shell $(CC) $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(DEBUG_CFLAGS) $(STD_CFLAGS) $(WARN_CFLAGS) $(NOWARN_CFLAGS) $(ERROR_CFLAGS) $(CFLAGS) -dM -E -xc - </dev/null 2>/dev/null | grep -c 'LOCK_FREE.*1'),0)
+  ifneq ($(shell $(CC) $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(STD_CFLAGS) $(WARN_CFLAGS) $(NOWARN_CFLAGS) $(ERROR_CFLAGS) $(CFLAGS) -dM -E -xc - </dev/null 2>/dev/null | grep -c 'LOCK_FREE.*1'),0)
     USE_LIBATOMIC   = implicit
   endif
 endif
@@ -859,10 +864,10 @@ endif
 $(collect_opts_flags)
 
 #### Global compile options
-VERBOSE_CFLAGS = $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(DEBUG_CFLAGS) $(STD_CFLAGS) $(TARGET_CFLAGS) $(CFLAGS) $(DEFINE)
+VERBOSE_CFLAGS = $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(STD_CFLAGS) $(TARGET_CFLAGS) $(CFLAGS) $(DEFINE)
 COPTS  = -Iinclude
 
-COPTS += $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(DEBUG_CFLAGS) $(STD_CFLAGS) $(WARN_CFLAGS) $(NOWARN_CFLAGS) $(ERROR_CFLAGS) $(TARGET_CFLAGS) $(DEFINE) $(SILENT_DEFINE)
+COPTS += $(OPT_CFLAGS) $(ARCH_FLAGS) $(CPU_CFLAGS) $(STD_CFLAGS) $(WARN_CFLAGS) $(NOWARN_CFLAGS) $(ERROR_CFLAGS) $(TARGET_CFLAGS) $(DEFINE) $(SILENT_DEFINE)
 COPTS += $(DEBUG) $(OPTIONS_CFLAGS) $(CFLAGS) $(ADDINC)
 
 ifneq ($(VERSION)$(SUBVERS)$(EXTRAVERSION),)
@@ -1170,7 +1175,6 @@ opts:
 	@echo -n 'OPT_CFLAGS="$(strip $(OPT_CFLAGS))" '
 	@echo -n 'ARCH_FLAGS="$(strip $(ARCH_FLAGS))" '
 	@echo -n 'CPU_CFLAGS="$(strip $(CPU_CFLAGS))" '
-	@echo -n 'DEBUG_CFLAGS="$(strip $(DEBUG_CFLAGS))" '
 	@echo -n 'STD_CFLAGS="$(strip $(STD_CFLAGS))" '
 	@echo -n 'WARN_CFLAGS="$(strip $(WARN_CFLAGS))" '
 	@echo -n 'NOWARN_CFLAGS="$(strip $(NOWARN_CFLAGS))" '