Merge #10808: Avoid some new gcc warnings in 15

c73b8be24 Explicitly initialize prevector::_union to avoid new warning (Matt Corallo)
1016dacfa Fix signed/unsigned comparison warning introduced in c8e29d7ff0. (Matt Corallo)

Tree-SHA512: d1574b0fdc9bfddc3517c382d34418b1d8ed80c81d2f6fd19378c064af8d7704fb84ef8b740ff97f7ec7609bd6de76348921fcc227e1ce97127947a0d22c7887

src/core_read.cpp

@@ -27,7 +27,7 @@ CScript ParseScript(const std::string& s)
 
     if (mapOpNames.empty())
     {
-        for (int op = 0; op <= MAX_OPCODE; op++)
+        for (unsigned int op = 0; op <= MAX_OPCODE; op++)
         {
             // Allow OP_RESERVED to get into mapOpNames
             if (op < OP_NOP && op != OP_RESERVED)

src/prevector.h

@@ -220,7 +220,7 @@ public:
         }
     }
 
-    prevector() : _size(0) {}
+    prevector() : _size(0), _union{{}} {}
 
     explicit prevector(size_type n) : _size(0) {
         resize(n);