gcc48 won't build under El Capitan; cannot fix Availability.h

[James Linder]

> On 28 Oct 2015, at 3:00 am, macports-users-request at lists.macosforge.org wrote:
> 
>> Tickets 
>> 
>> #48471 https://trac.macports.org/ticket/48471
>> 
>> #49381 https://trac.macports.org/ticket/49381
>> 
>> both refer to build failures under El Capitan (in my case, OS X 10.11.1) involving gcc48.
>> 
>> I migrated macports from Yosemite to El Capitan per usual steps. Some 72 ports would not reinstall, most if not all due to the gcc48 problem indicated in those tickets.
>> 
>> The issue is not just that gcc48 cannot be used for certain other port builds, but:
>> 
>>  gcc48 itself fails to build.
>> 
>> Following suggestions at #48471, I tried to edit Availability.h. But even using sudo with an admin account, OS X refused to allow me to edit Availability.h.
>> 
>> As a number of the ports involved will not install, with their needed variants, using later versions of gcc, including gcc48, using a different version is not a solution. (gcc 47, gcc49, and gcc5 did reinstall OK.)
>> 
>> What's to be done?
> 
> For the ports that specify gcc48 as a default variant: update them, if possible to use gcc5 as a default variant.
> 
> For those that absolutely require gcc48: wait for Apple to fix /usr/include/Availability.h.

You are surely encountering the rootless os SID features.
As an utter heathen I find the concept totally repulsive so 
http://www.macworld.com/article/2986118/security/how-to-modify-system-integrity-protection-in-el-capitan.html

James