ICU-22800 Avoid inconsistent state inside Locale

There are some memory leak in Locale which is hard to figure out why.
Use different variable to track memory allocation to avoid inconsistent
state while malloc fail

icu4c/source/common/locid.cpp

@@ -1869,11 +1869,11 @@ Locale& Locale::init(const char* localeID, UBool canonicalize)
         if(err == U_BUFFER_OVERFLOW_ERROR || length >= (int32_t)sizeof(fullNameBuffer)) {
             U_ASSERT(baseName == nullptr);
             /*Go to heap for the fullName if necessary*/
-            fullName = (char *)uprv_malloc(sizeof(char)*(length + 1));
-            if (fullName == nullptr) {
-                fullName = fullNameBuffer;
+            char* newFullName = (char *)uprv_malloc(sizeof(char)*(length + 1));
+            if (newFullName == nullptr) {
                 break; // error: out of memory
             }
+            fullName = newFullName;
             err = U_ZERO_ERROR;
             length = canonicalize ?
                 uloc_canonicalize(localeID, fullName, length+1, &err) :
@@ -1992,11 +1992,12 @@ Locale::initBaseName(UErrorCode &status) {
     if (atPtr && eqPtr && atPtr < eqPtr) {
         // Key words exist.
         int32_t baseNameLength = (int32_t)(atPtr - fullName);
-        baseName = (char *)uprv_malloc(baseNameLength + 1);
-        if (baseName == nullptr) {
+        char* newBaseName = (char *)uprv_malloc(baseNameLength + 1);
+        if (newBaseName == nullptr) {
             status = U_MEMORY_ALLOCATION_ERROR;
             return;
         }
+        baseName = newBaseName;
         uprv_strncpy(baseName, fullName, baseNameLength);
         baseName[baseNameLength] = 0;