Fix alloc-dealloc-mismatch in vecNewEnviron

    ==2654441==ERROR: AddressSanitizer: alloc-dealloc-mismatch (operator new [] vs operator delete) on 0x6020000c0330
        #0 0x7f264e95e009 in operator delete(void*, unsigned long) /build/gcc/src/gcc/libsanitizer/asan/asan_new_delete.cpp:172
        #1 0x5645ddfcef1e in steamcompmgr_main(int, char**) ../src/steamcompmgr.cpp:2602
    Running Steam on arch rolling 64-bit
        #2 0x5645de0020e6 in steamCompMgrThreadRun() ../src/main.cpp:126
        #3 0x5645de001a2f in void std::__invoke_impl<void, void (*)()>(std::__invoke_other, void (*&&)()) /usr/include/c++/10.2.0/bits/invoke.h:60
        #4 0x5645de001899 in std::__invoke_result<void (*)()>::type std::__invoke<void (*)()>(void (*&&)()) /usr/include/c++/10.2.0/bits/invoke.h:95
        #5 0x5645de001757 in void std::thread::_Invoker<std::tuple<void (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>) /usr/include/c++/10.2.0/thread:264
        #6 0x5645de00161a in std::thread::_Invoker<std::tuple<void (*)()> >::operator()() /usr/include/c++/10.2.0/thread:271
        #7 0x5645de000d98 in std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (*)()> > >::_M_run() /usr/include/c++/10.2.0/thread:215
    STEAM_RUNTIME is enabled automatically
        #8 0x7f264e143c23 in execute_native_thread_routine /build/gcc/src/gcc/libstdc++-v3/src/c++11/thread.cc:80
        #9 0x7f264d58b3e8 in start_thread (/usr/lib/libpthread.so.0+0x93e8)
        #10 0x7f264d4b9292 in __GI___clone (/usr/lib/libc.so.6+0x100292)

Fixes: 4a5cd5d ("steamcompmgr: disable Steam overlay for sub-command")

src/steamcompmgr.cpp

@@ -2452,7 +2452,7 @@ steamcompmgr_main (int argc, char **argv)
 		{
 			if ( vecNewEnviron[ i ] != nullptr )
 			{
-				delete vecNewEnviron[ i ];
+				delete[] vecNewEnviron[ i ];
 			}
 		}