Addressed comments from swiftlang/swift#25147. (tensorflow#140)

Simplify `_ExecutionContext.init()` runtime initialization code.

Author: eaplatanios

Sources/TensorFlow/Core/Runtime.swift

@@ -569,6 +569,12 @@ public final class _ExecutionContext {
         // Initialize the TF runtime exactly once. Only affects local execution
         // (when _RuntimeConfig.tensorFlowServer is set to "").
         if !_RuntimeConfig.tensorFlowRuntimeInitialized {
+            // Install a signal handler to ensure we exit when interrupted.
+            signal(SIGINT) { _ in
+                print("Caught interrupt signal, exiting...")
+                exit(1)
+            }
+            
             var args = ["dummyProgramName"]
             if _RuntimeConfig.printsDebugLog {
                 args.append("--alsologtostderr")
@@ -588,24 +594,19 @@ public final class _ExecutionContext {
 
             // Calculate the addresses of all the strings within our single buffer, and then call
             // TF_InitMain.
-            flattenedStringBytes.withUnsafeMutableBufferPointer { flattenedStringBytesBuffer in
+            flattenedStringBytes.withUnsafeMutableBufferPointer { buffer in
                 var stringAddrs: [UnsafeMutablePointer<Int8>?] = []
-                var currentStringAddr = flattenedStringBytesBuffer.baseAddress
+                var currentStringAddr = buffer.baseAddress
                     .map(UnsafeMutablePointer.init)
                 for length in lengths {
                     stringAddrs.append(currentStringAddr)
                     currentStringAddr = currentStringAddr?.advanced(by: length)
                 }
 
                 stringAddrs.withUnsafeMutableBufferPointer { stringAddrsBuffer in
-                    var cArgs = [stringAddrsBuffer.baseAddress.map(UnsafeMutablePointer.init)]
-                    var cArgsCount = [Int32(args.count)]
-
-                    cArgs.withUnsafeMutableBufferPointer { cArgsBuffer in
-                        cArgsCount.withUnsafeMutableBufferPointer { cArgsCountBuffer in
-                            TF_InitMain(nil, cArgsCountBuffer.baseAddress, cArgsBuffer.baseAddress)
-                        }
-                    }
+                    var cArgsCount = Int32(args.count)
+                    var cArgs = stringAddrsBuffer.baseAddress.map(UnsafeMutablePointer.init)
+                    TF_InitMain(nil, &cArgsCount, &cArgs)
                 }
             }
             _RuntimeConfig.tensorFlowRuntimeInitialized = true