Give end-marker symbols their own addresses to work around a linker bug (#66999)

It seems there is a linker bug related to control-flow guard that is
causing #66969. In eb8460fd a thunktemplates.asm file was added that has
a LEAF_END_MARKED at the end of the file. This creates two symbols for
the same upcoming address. Normally that should be fine, but in this
case it causes the linker to place the same address twice in a CFG table
in the PE file. This causes the kernel to fail while loading the image.

A simple workaround would be to add a nop at the end of
thunktemplates.asm, but @janvorli suggested giving these symbols their
own address in all cases for goodness when debugging. We already do so
for Windows x64 it looks like.

Fix #66969

src/coreclr/pal/inc/unixasmmacrosamd64.inc

@@ -52,6 +52,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro NOP_6_BYTE

src/coreclr/pal/inc/unixasmmacrosarm.inc

@@ -40,6 +40,8 @@ C_FUNC(\Name):
         .global C_FUNC(\Name\()_End)
 C_FUNC(\Name\()_End):
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PREPARE_EXTERNAL_VAR Name, HelperReg

src/coreclr/pal/inc/unixasmmacrosarm64.inc

@@ -44,6 +44,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PREPARE_EXTERNAL_VAR Name, HelperReg

src/coreclr/pal/inc/unixasmmacrosx86.inc

@@ -33,6 +33,8 @@ C_FUNC(\Name):
 C_FUNC(\Name\()_End):
         .global C_FUNC(\Name\()_End)
         LEAF_END \Name, \Section
+        // make sure this symbol gets its own address
+        nop
 .endm
 
 .macro PROLOG_BEG

src/coreclr/vm/amd64/AsmMacros.inc

@@ -133,12 +133,13 @@ Section ends
 LEAF_END_MARKED macro Name, section
         public Name&_End
 Name&_End label qword
+
+Name    endp
+
         ; this nop is important to keep the label in
         ; the right place in the face of BBT
         nop
 
-Name    endp
-
 Section ends
 
         endm

src/coreclr/vm/arm/asmmacros.h

@@ -29,6 +29,9 @@ $__EndLabelName
 
     LEAF_END $FuncName
 
+    ; Make sure this symbol gets its own address
+    nop
+
     MEND
 
 ;-----------------------------------------------------------------------------

src/coreclr/vm/arm64/asmmacros.h

@@ -147,6 +147,9 @@ $__EndLabelName
 
     LEAF_END $FuncName
 
+    ; make sure this symbol gets its own address
+    nop
+
     MEND
 ;-----------------------------------------------------------------------------
 ; Macro use for enabling C++ to know where to patch code at runtime.

src/coreclr/vm/i386/AsmMacros.inc

@@ -38,6 +38,8 @@ LEAF_END_MARKED macro functionName
     %endMarkerName:
     PUBLIC endMarkerName
     functionName ENDP
+    ; make sure this symbol gets its own address
+    nop
 endm
 
 PATCH_LABEL macro labelName