Default initialize fixed point Eigen types.

In certain cases, tensors are filled with default values of the type. But, for these fixed point types, these values were uninitialized. Thus, we would have uninitialized memory access bugs, some of which were caught by MSAN.

PiperOrigin-RevId: 344101137
Change-Id: I14555fda74dca3b5f1582da9008901937e3f14e2

third_party/eigen3/unsupported/Eigen/CXX11/src/FixedPoint/FixedPointTypes.h

@@ -49,7 +49,7 @@ struct scalar_product_traits<QInt32, double> {
 // the compiler from silently type cast the mantissa into a bigger or a smaller
 // representation.
 struct QInt8 {
-  QInt8() {}
+  QInt8() : value(0) {}
   QInt8(const int8_t v) : value(v) {}
   QInt8(const QInt32 v);
 
@@ -59,7 +59,7 @@ struct QInt8 {
 };
 
 struct QUInt8 {
-  QUInt8() {}
+  QUInt8() : value(0) {}
   QUInt8(const uint8_t v) : value(v) {}
   QUInt8(const QInt32 v);
 
@@ -69,7 +69,7 @@ struct QUInt8 {
 };
 
 struct QInt16 {
-  QInt16() {}
+  QInt16() : value(0) {}
   QInt16(const int16_t v) : value(v) {}
   QInt16(const QInt32 v);
   operator int() const { return static_cast<int>(value); }
@@ -78,7 +78,7 @@ struct QInt16 {
 };
 
 struct QUInt16 {
-  QUInt16() {}
+  QUInt16() : value(0) {}
   QUInt16(const uint16_t v) : value(v) {}
   QUInt16(const QInt32 v);
   operator int() const { return static_cast<int>(value); }
@@ -87,7 +87,7 @@ struct QUInt16 {
 };
 
 struct QInt32 {
-  QInt32() {}
+  QInt32() : value(0) {}
   QInt32(const int8_t v) : value(v) {}
   QInt32(const int32_t v) : value(v) {}
   QInt32(const uint32_t v) : value(static_cast<int32_t>(v)) {}