use and append existing compile flags

[ghost]

Fix for : #17

If the system has overridden LDFLAGS - for example, because of a non-standard homebrew install location - then the LDFLAGS flag will not be set correctly (-arch x86_64).

This patch appends the build specific settings, meaning the existing system overrides will be respected.

Personally, I'd leave the optimisation settings (-O3) to the users discression, but that's unimportant for this fix.

[ghost]

Also fixed the elixir compilation failure :

/code/common/horde_test/ DEBUG=1 mix compile                                                                                                                                      
==> prometheus_process_collector                                                                                                                                                  
make: *** No targets specified and no makefile found.  Stop.                                                                                                                      
could not compile dependency :prometheus_process_collector, "mix compile" failed. You can recompile this dependency with "mix deps.compile prometheus_process_collector", update it with "mix deps.update prometheus_process_collector" or clean it with "mix deps.clean prometheus_process_collector"                                                              
==> horde_test                                                                                                                                                                    
** (Mix) Could not compile with "make" (exit status: 2).                                                                                                                          
You need to have gcc and make installed. Try running the                                                                                                                          
commands "gcc --version" and / or "make --version". If these programs                                                                                                             
are not installed, you will be prompted to install them.

The error message is misleading - actual problem is that the makefile is in the c_src directory - setting the parameter 'make_cwd' to "c_src" correctly points it to the Makefile in that directory.

[ghost]

Also with regard to the Travis failure - I'm seeing the same kind of error accross a slew of Erlang/Elixir projects - suggest we ignore the erlang 18 fail.

https://twitter.com/binarytemple/status/1170617945208381441

[ghost]

@deadtrickster @happysalada - you like ?

[deadtrickster]

Hi, I do indeed. Can you please remove OTP 18 then? Really love green builds

[ghost]

Hi, I do indeed. Can you please remove OTP 18 then? Really love green builds

@deadtrickster Completed - with regards - tya brah

[deadtrickster]

Thanks, will push to hex sometime soon