yosys: remove pointless patching

This fixes the patch introduced in:

  94a047ca74 (yosys: fix build on darwin, 2021-11-09)

Because we supply yosys with an external build of ABC, the patched
ABCMKARGS variable is without influence. Even if we were building with
in-tree ABC, that part of the patch is wrong, so drop it altogether.

pkgs/development/compilers/yosys/fix-clang-build.patch

@@ -2,19 +2,6 @@ diff --git a/Makefile b/Makefile
 index 86abc6958..a72f7b792 100644
 --- a/Makefile
 +++ b/Makefile
-@@ -145,7 +145,12 @@ bumpversion:
- ABCREV = 4f5f73d
- ABCPULL = 1
- ABCURL ?= https://github.com/YosysHQ/abc
-+
-+ifneq ($(CONFIG),clang)
-+ABCMKARGS = CC=clang CXX="$(CXX)" LD=clang ABC_USE_LIBSTDCXX=1 VERBOSE=$(Q)
-+else
- ABCMKARGS = CC="$(CXX)" CXX="$(CXX)" ABC_USE_LIBSTDCXX=1 VERBOSE=$(Q)
-+endif
- 
- # set ABCEXTERNAL = <abc-command> to use an external ABC instance
- # Note: The in-tree ABC (yosys-abc) will not be installed when ABCEXTERNAL is set.
 @@ -187,7 +192,7 @@ endif
  endif