[mlir][sparse] Improving the FATAL macro

[wrengr]

Summary

The previous macro definition using {...} would fail to compile when the callsite uses a semicolon followed by an else-statement (i.e., if (...) FATAL(...); else ...;). Replacing the simple braces with do{...}while(0) (n.b., semicolon not included in the macro definition) enables callsites to use the semicolon plus else-statement syntax without problems. The new definition now requires the semicolon at all callsites, but since it was already being called that way nothing changes.

For more explanation, see https://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html

[wrengr]

rebase (attempting to fix the spurious Debian build failure before landing)

[wrengr]

rebasing for D126233

mlir/lib/ExecutionEngine/SparseTensorUtils.cpp

 }
 
 // This macro helps minimize repetition of this idiom, as well as ensuring
 // we have some additional output indicating where the error is coming from.
 // (Since `fprintf` doesn't provide a stacktrace, this helps make it easier
 // to track down whether an error is coming from our code vs somewhere else
 // in MLIR.)
 #define FATAL(...)                                                             \
-  {                                                                            \
+  do {                                                                         \
     fprintf(stderr, "SparseTensorUtils: " __VA_ARGS__);                        \
     exit(1);                                                                   \
-  }
+  } while (0)
 
 // TODO: try to unify this with `SparseTensorFile::assertMatchesShape`
 // which is used by `openSparseTensorCOO`.  It's easy enough to resolve
 // the `std::vector` vs pointer mismatch for `dimSizes`; but it's trickier
 // to resolve the presence/absence of `perm` (without introducing extra
 // overhead), so perhaps the code duplication is unavoidable.
 //
 /// Asserts that the `dimSizes` (in target-order) under the `perm` (mapping