use system zlib if available (client only)

CHANGELOG.md

@@ -13,6 +13,7 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
  - Change, use system Lua library if available (@doegox)
  - Change, use system Jansson library if available (@doegox)
  - Change, use system Whereami library if available (@doegox)
+ - Change, use system Zlib library if available (@doegox)
  - Fix release version information (@doegox)
 
 ## [ice coffee.4.9237][2020-05-21]

client/Makefile

@@ -165,6 +165,15 @@ INCLUDES += $(WAILIBINC)
 
 ## Zlib
 # system library useable? Need to recompress hardnested tables?
+ifneq ($(SKIPZLIBSYSTEM),1)
+    ZLIBINCLUDES = $(shell $(PKG_CONFIG_ENV) pkg-config --cflags zlib 2>/dev/null)
+    ZLIBLDLIBS = $(shell $(PKG_CONFIG_ENV) pkg-config --libs zlib 2>/dev/null)
+    ifneq ($(ZLIBLDLIBS),)
+        ZLIB = $(ZLIBLDLIBS)
+        ZLIBINC = $(ZLIBINCLUDES)
+        ZLIB_FOUND = 1
+    endif
+endif
 LDLIBS +=$(ZLIB)
 INCLUDES += $(ZLIBINC)
 
@@ -328,6 +337,10 @@ ifeq ($(WAI_FOUND),1)
     $(info Whereami library:  system library found)
 endif
 
+ifeq ($(ZLIB_FOUND),1)
+    $(info Zlib library:      system library found)
+endif
+
 $(info compiler version:  $(shell $(CC) --version|head -n 1))
 $(info ===================================================================)
 
@@ -622,8 +635,10 @@ mbedtls:
 	$(Q)$(MAKE) --no-print-directory -C $(MBEDTLSLIBPATH) OBJDIR=$(ROOT_DIR)$(OBJDIR) BINDIR=$(ROOT_DIR)$(OBJDIR) all
 
 zlib:
+ifneq ($(ZLIB_FOUND),1)
 	$(info [*] MAKE $@)
 	$(Q)$(MAKE) --no-print-directory -C $(ZLIBPATH) OBJDIR=$(ROOT_DIR)$(OBJDIR) BINDIR=$(ROOT_DIR)$(OBJDIR) all
+endif
 
 ########
 # misc #

doc/md/Development/Maintainers.md

@@ -62,7 +62,9 @@ It's also possible to skip parts even if libraries are present in the compilatio
 * `make client SKIPQT=1` to skip GUI even if Qt is present
 * `make client SKIPBT=1` to skip native Bluetooth support even if libbluetooth is present
 * `make client SKIPLUASYSTEM=1` to skip system Lua lib even if liblua5.2 is present, use embedded Lua lib instead
+* `make client SKIPJANSSONSYSTEM=1` to skip system Jansson lib even if libjansson is present, use embedded Jansson lib instead
 * `make client SKIPWHEREAMISYSTEM=1` to skip system Whereami lib even if libwhereami is present, use embedded whereami lib instead
+* `make client SKIPZLIBSYSTEM=1` to skip system Zlib even if libz is present, use embedded Zlib instead
 
 If you're cross-compiling, these ones might be useful: