[llvm-exegesis] Remove redundant declarations (NFC) (#166086)

Identified with readability-redundant-declaration.

Author: kazutakahirata

llvm/unittests/tools/llvm-exegesis/PowerPC/TargetTest.cpp

@@ -20,9 +20,6 @@
 
 namespace llvm{
 namespace exegesis {
-
-void InitializePowerPCExegesisTarget();
-
 namespace {
 
 using testing::NotNull;

llvm/unittests/tools/llvm-exegesis/RISCV/TargetTest.cpp

@@ -20,9 +20,6 @@
 
 namespace llvm {
 namespace exegesis {
-
-void InitializeRISCVExegesisTarget();
-
 namespace {
 
 using testing::IsEmpty;

llvm/unittests/tools/llvm-exegesis/X86/SnippetFileTest.cpp

@@ -23,9 +23,6 @@
 
 namespace llvm {
 namespace exegesis {
-
-void InitializeX86ExegesisTarget();
-
 namespace {
 
 using testing::ElementsAre;

llvm/unittests/tools/llvm-exegesis/X86/SnippetGeneratorTest.cpp

@@ -20,9 +20,6 @@
 
 namespace llvm {
 namespace exegesis {
-
-void InitializeX86ExegesisTarget();
-
 namespace {
 
 using testing::AnyOf;

llvm/unittests/tools/llvm-exegesis/X86/SnippetRepetitorTest.cpp

@@ -16,9 +16,6 @@
 
 namespace llvm {
 namespace exegesis {
-
-void InitializeX86ExegesisTarget();
-
 namespace {
 
 using testing::ElementsAre;

llvm/unittests/tools/llvm-exegesis/X86/TargetTest.cpp

@@ -53,9 +53,6 @@ bool operator==(const MCInst &a, const MCInst &b) {
 
 namespace llvm {
 namespace exegesis {
-
-void InitializeX86ExegesisTarget();
-
 namespace {
 
 using testing::AllOf;