Remove unused exception parameter from xplat/safe_image/io/ImageInfo.cpp

Summary:
`-Wunused-exception-parameter` has identified an unused exception parameter. This diff removes it.

This:
```
try {
    ...
} catch (exception& e) {
    // no use of e
}
```
should instead be written as
```
} catch (exception&) {
```

If the code compiles, this is safe to land.

Reviewed By: dmm-fb

Differential Revision: D60516143

fbshipit-source-id: 14f13290af21103d1c1ad38d708817376b3d6681

xplat/FlipperTests/FlipperConnectionManagerImplTerminationTests.cpp

@@ -44,7 +44,7 @@ TEST_F(
         state,
         contextStore);
     FAIL();
-  } catch (std::invalid_argument& e) {
+  } catch (std::invalid_argument&) {
     // Pass test
   }
   try {
@@ -53,7 +53,7 @@ TEST_F(
         state,
         contextStore);
     FAIL();
-  } catch (std::invalid_argument& e) {
+  } catch (std::invalid_argument&) {
     // Pass test
   }
 }