add gpiod lib prebuilt binaries for linux

linux/lib/README.md

@@ -0,0 +1,6 @@
+# linux/lib/gpiod
+
+This is a nasty hack because the current ubuntu has an old version of libgpiod and I don't want to make others have to build that lib from source.
+Once ubuntu 21.04 is out I think this problem will be solved.
+
+-@geeksville

linux/lib/libgpiod.la

@@ -0,0 +1,41 @@
+# libgpiod.la - a libtool library file
+# Generated by libtool (GNU libtool) 2.4.6 Debian-2.4.6-14
+#
+# Please DO NOT delete this file!
+# It is necessary for linking the library.
+
+# The name that we can dlopen(3).
+dlname='libgpiod.so.2'
+
+# Names of this library.
+library_names='libgpiod.so.2.2.1 libgpiod.so.2 libgpiod.so'
+
+# The name of the static archive.
+old_library='libgpiod.a'
+
+# Linker flags that cannot go in dependency_libs.
+inherited_linker_flags=''
+
+# Libraries that this one depends upon.
+dependency_libs=''
+
+# Names of additional weak libraries provided by this library
+weak_library_names=''
+
+# Version information for libgpiod.
+current=4
+age=2
+revision=1
+
+# Is this an already installed library?
+installed=yes
+
+# Should we warn about portability when linking against -modules?
+shouldnotlink=no
+
+# Files to dlopen/dlpreopen
+dlopen=''
+dlpreopen=''
+
+# Directory that this library needs to be installed in:
+libdir='/usr/local/lib'

platformio.ini

@@ -9,7 +9,7 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [platformio]
-default_envs = tbeam
+;default_envs = tbeam
 ;default_envs = tbeam0.7
 ;default_envs = heltec-v2.0
 ;default_envs = tlora-v1
@@ -18,7 +18,7 @@ default_envs = tbeam
 ;default_envs = lora-relay-v1 # nrf board
 ;default_envs = t-echo
 ;default_envs = nrf52840dk-geeksville
-;default_envs = native # lora-relay-v1 # nrf52840dk-geeksville # linux # or if you'd like to change the default to something like lora-relay-v1 put that here
+default_envs = native # lora-relay-v1 # nrf52840dk-geeksville # linux # or if you'd like to change the default to something like lora-relay-v1 put that here
 ;default_envs = rak4631
 ;default_envs = rak4630
 
@@ -429,7 +429,7 @@ lib_deps =
 [env:native]
 platform = https://github.com/geeksville/platform-native.git 
 src_filter = ${env.src_filter} -<esp32/> -<nimble/> -<nrf52/> -<mesh/http/> -<plugins/esp32>
-build_flags = ${arduino_base.build_flags} -O0 -lgpiod
+build_flags = ${arduino_base.build_flags} -O0 -lgpiod -Llinux/lib
 framework = arduino
 board = native
 lib_deps =