AK+LibGfx+LibJS: Pass -1 as the file descriptor to anonymous mmap

Serenity/Linux/macOS ignore the file descriptor when an anonymous
mapping is requested. However, BSDs require the fd to be -1.

AK/BumpAllocator.h

@@ -106,7 +106,7 @@ protected:
 #ifdef __serenity__
                 new_chunk = serenity_mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_RANDOMIZED | MAP_PRIVATE, 0, 0, m_chunk_size, "BumpAllocator Chunk");
 #else
-                new_chunk = mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+                new_chunk = mmap(nullptr, m_chunk_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
 #endif
                 if (new_chunk == MAP_FAILED)
                     return false;

Userland/Libraries/LibGfx/Bitmap.cpp

@@ -558,7 +558,7 @@ ErrorOr<BackingStore> Bitmap::allocate_backing_store(BitmapFormat format, IntSiz
     map_flags |= MAP_PURGEABLE;
     void* data = mmap_with_name(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, 0, 0, String::formatted("GraphicsBitmap [{}]", size).characters());
 #else
-    void* data = mmap(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, 0, 0);
+    void* data = mmap(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, -1, 0);
 #endif
     if (data == MAP_FAILED)
         return Error::from_errno(errno);

Userland/Libraries/LibJS/Bytecode/BasicBlock.cpp

@@ -23,7 +23,7 @@ BasicBlock::BasicBlock(String name, size_t size)
     // The main issue we're working around here is that we don't want pointers into the bytecode stream to become invalidated
     // during code generation due to dynamic buffer resizing. Otherwise we could just use a Vector.
     m_buffer_capacity = size;
-    m_buffer = (u8*)mmap(nullptr, m_buffer_capacity, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+    m_buffer = (u8*)mmap(nullptr, m_buffer_capacity, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
     VERIFY(m_buffer != MAP_FAILED);
 }