[libc] Increase the number of times we wait on a slab

Summary:
This wait restricts how long we wait on a slab. The only reason this
isn't an infinite loop is to prevent complete deadlocks. However, this
limit was *just* on the cusp of waiting long enough for the allocation
to be done. Just increase this to a sufficiently large value, because
this limit only exists to keep the interface wait-free in the absolute
worst case scheduling scenario. This *MASSIVELY* improved performance
for mixed allocations as we no longer shuffled around creating more than
necessary.

Author: jhuber6

libc/src/__support/GPU/allocator.cpp

@@ -37,7 +37,7 @@ constexpr static uint32_t MIN_SIZE = 16;
 constexpr static uint32_t MIN_ALIGNMENT = MIN_SIZE - 1;
 
 // The number of times to attempt claiming an in-progress slab allocation.
-constexpr static uint32_t MAX_TRIES = 128;
+constexpr static uint32_t MAX_TRIES = 1024;
 
 // A sentinel used to indicate an invalid but non-null pointer value.
 constexpr static uint64_t SENTINEL = cpp::numeric_limits<uint64_t>::max();