[BUILD] include <cstdint>

[dbolduc]

We have a build that uses opentelemetry-cpp with C++20. It failed to compile the latest release (v1.10.0).
full log.

[11/66] Building CXX object sdk/src/metrics/CMakeFiles/opentelemetry_metrics.dir/data/circular_buffer.cc.o
FAILED: sdk/src/metrics/CMakeFiles/opentelemetry_metrics.dir/data/circular_buffer.cc.o 
/usr/bin/c++ -DHAVE_ABSEIL -Dopentelemetry_metrics_EXPORTS -I/var/tmp/build/api/include -I/var/tmp/build/sdk/include -I/var/tmp/build/sdk -I/var/tmp/build/ext/include -O3 -DNDEBUG -std=gnu++20 -fPIC -Wno-error=deprecated-declarations -MD -MT sdk/src/metrics/CMakeFiles/opentelemetry_metrics.dir/data/circular_buffer.cc.o -MF sdk/src/metrics/CMakeFiles/opentelemetry_metrics.dir/data/circular_buffer.cc.o.d -o sdk/src/metrics/CMakeFiles/opentelemetry_metrics.dir/data/circular_buffer.cc.o -c /var/tmp/build/sdk/src/metrics/data/circular_buffer.cc
In file included from /var/tmp/build/sdk/src/metrics/data/circular_buffer.cc:4:
/var/tmp/build/sdk/include/opentelemetry/sdk/metrics/data/circular_buffer.h:44:32: error: 'uint64_t' has not been declared
   44 |   void Increment(size_t index, uint64_t count);
      |                                ^~~~~~~~
/var/tmp/build/sdk/include/opentelemetry/sdk/metrics/data/circular_buffer.h:52:3: error: 'uint64_t' does not name a type
   52 |   uint64_t Get(size_t index) const;
      |   ^~~~~~~~
/var/tmp/build/sdk/include/opentelemetry/sdk/metrics/data/circular_buffer.h:9:1: note: 'uint64_t' is defined in header '<cstdint>'; did you forget to '#include <cstdint>'?
    8 | #include <limits>
  +++ |+#include <cstdint>
    9 | #include <vector>

Our build command is something like:
https://github.com/googleapis/google-cloud-cpp/blob/8c960f3f9cd862f20888a610f4c07920bb57d4c5/ci/cloudbuild/dockerfiles/fedora-37-cxx20.Dockerfile#L183-L195

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: dbolduc / name: Darren Bolduc (c82d669)

[ThomsonTan]

Thanks for the fix.

[codecov]

Codecov Report

Merging #2230 (c82d669) into main (ca8c234) will decrease coverage by 0.02%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2230      +/-   ##
==========================================
- Coverage   87.31%   87.29%   -0.02%     
==========================================
  Files         169      169              
  Lines        4901     4901              
==========================================
- Hits         4279     4278       -1     
- Misses        622      623       +1     

Impacted Files	Coverage Δ
...e/opentelemetry/sdk/metrics/data/circular_buffer.h	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

[dbolduc]

Does this fix warrant a v1.10.1 patch release?