[flang][test] Fix REQUIRES and options for a few x86 specific tests (llvm#146872)

These should have been looking for the "x86" target not "x64_64".

When run on AArch64 they failed because bbc tried to compile for
AArch64. Add a target option to fix that, as these tests are x86
specific.

Author: DavidSpickett

flang/test/Lower/Intrinsics/product.f90

@@ -1,5 +1,5 @@
-! REQUIRES: x86_64-registered-target
-! RUN: bbc --use-desc-for-alloc=false -emit-fir -hlfir=false %s -o - | FileCheck %s
+! REQUIRES: x86-registered-target
+! RUN: bbc -target x86_64-unknown-linux-gnu --use-desc-for-alloc=false -emit-fir -hlfir=false %s -o - | FileCheck %s
 
 ! CHECK-LABEL: func @_QPproduct_test(
 ! CHECK-SAME: %[[arg0:.*]]: !fir.box<!fir.array<?xi32>>{{.*}}) -> i32

flang/test/Lower/Intrinsics/sum.f90

@@ -1,5 +1,5 @@
-! REQUIRES: x86_64-registered-target
-! RUN: bbc --use-desc-for-alloc=false -emit-fir -hlfir=false %s -o - | FileCheck %s
+! REQUIRES: x86-registered-target
+! RUN: bbc -target x86_64-unknown-linux-gnu --use-desc-for-alloc=false -emit-fir -hlfir=false %s -o - | FileCheck %s
 
 ! CHECK-LABEL: func @_QPsum_test(
 ! CHECK-SAME: %[[arg0:.*]]: !fir.box<!fir.array<?xi32>>{{.*}}) -> i32 {

flang/test/Lower/complex-operations.f90

@@ -1,6 +1,6 @@
 ! REQUIRES: flang-supports-f128-math
-! REQUIRES: x86_64-registered-target
-! RUN: bbc -hlfir=false %s -o - | FileCheck %s
+! REQUIRES: x86-registered-target
+! RUN: bbc -target x86_64-unknown-linux-gnu -hlfir=false %s -o - | FileCheck %s
 
 ! CHECK-LABEL: @_QPadd_test
 subroutine add_test(a,b,c)