Delete null comparisons of non-null arguments (dotnet#27523)

Remove gcc nonnull-compare suppression and impossible conditions.

> error: nonnull argument 'this' compared to NULL
> [-Werror=nonnull-compare]

Author: am11

configurecompiler.cmake

@@ -256,7 +256,7 @@ if (MSVC)
   add_link_options($<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,SHARED_LIBRARY>:/SUBSYSTEM:WINDOWS,${WINDOWS_SUBSYSTEM_VERSION}>)
 
   set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} /IGNORE:4221")
-  
+
   add_link_options($<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>:/DEBUG>)
   add_link_options($<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>:/PDBCOMPRESS>)
   add_link_options($<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>:/STACK:1572864>)
@@ -312,7 +312,7 @@ elseif (CLR_CMAKE_PLATFORM_UNIX)
       endif ()
       if (${__UBSAN_POS} GREATER -1)
         # all sanitizier flags are enabled except alignment (due to heavy use of __unaligned modifier)
-        list(APPEND CLR_CXX_SANITIZERS 
+        list(APPEND CLR_CXX_SANITIZERS
           "bool"
           bounds
           enum
@@ -513,9 +513,6 @@ if (CLR_CMAKE_PLATFORM_UNIX)
   else()
     add_compile_options(-Wno-unused-but-set-variable)
     add_compile_options(-Wno-unknown-pragmas)
-    if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 7.0)
-      add_compile_options(-Wno-nonnull-compare)
-    endif()
     if (COMPILER_SUPPORTS_F_ALIGNED_NEW)
       add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-faligned-new>)
     endif()

src/ToolBox/superpmi/superpmi-shared/lightweightmap.h

@@ -373,7 +373,6 @@ class LightWeightMap : public LightWeightMapBuffer
 
     int GetIndex(_Key key)
     {
-        AssertCodeMsg(this != nullptr, EXCEPTIONCODE_MC, "There is no such LWM (in GetIndex)");
         if (numItems == 0)
             return -1;