[PATCH] rts: Fix invocation of __ieee_set_fp_control() on alpha-linux

[PATCH] rts: Fix invocation of __ieee_set_fp_control() on alpha-linux

Fixes the following error when building GHC on alpha-linux:

rts/posix/Signals.c: In function ‘initDefaultHandlers’:

rts/posix/Signals.c:709:5: error:
     error: implicit declaration of function ‘ieee_set_fp_control’ [-Wimplicit-function-declaration]
      709 |     ieee_set_fp_control(0);
          |     ^~~~~~~~~~~~~~~~~~~
    |
709 |     ieee_set_fp_control(0);
    |

Gbp-Pq: Name alpha-fix-ieee_set_fp_control-invocation.patch