Fix some typos in identifiers. (#7118)

src/api/z3_api.h

@@ -1363,7 +1363,7 @@ typedef enum {
    - Z3_NO_PARSER:     Parser output is not available, that is, user didn't invoke #Z3_parse_smtlib2_string or #Z3_parse_smtlib2_file.
    - Z3_INVALID_PATTERN: Invalid pattern was used to build a quantifier.
    - Z3_MEMOUT_FAIL:   A memory allocation failure was encountered.
-   - Z3_FILE_ACCESS_ERRROR: A file could not be accessed.
+   - Z3_FILE_ACCESS_ERROR: A file could not be accessed.
    - Z3_INVALID_USAGE:   API call is invalid in the current state.
    - Z3_INTERNAL_FATAL: An error internal to Z3 occurred.
    - Z3_DEC_REF_ERROR: Trying to decrement the reference counter of an AST that was deleted or the reference counter was not initialized with #Z3_inc_ref.

src/smt/theory_arith_int.h

@@ -99,7 +99,7 @@ namespace smt {
         theory_var result = null_theory_var;
         numeral range;
         numeral new_range;
-        numeral small_range_thresold(1024);
+        numeral small_range_threshold(1024);
         unsigned n = 0;
         for (row const& row : m_rows) {
             theory_var v = row.get_base_var();
@@ -117,7 +117,7 @@ namespace smt {
             numeral const & u = upper_bound(v).get_rational();
             new_range  = u;
             new_range -= l;
-            if (new_range > small_range_thresold) {
+            if (new_range > small_range_threshold) {
                 //
             }
             else if (result == null_theory_var || new_range < range) {

src/util/sexpr.cpp

@@ -26,11 +26,11 @@ Notes:
 #endif
 
 struct sexpr_composite : public sexpr {
-    unsigned m_num_chilren;
+    unsigned m_num_children;
     sexpr *  m_children[0];
     sexpr_composite(unsigned num_children, sexpr * const * children, unsigned line, unsigned pos):
         sexpr(kind_t::COMPOSITE, line, pos),
-        m_num_chilren(num_children) {
+        m_num_children(num_children) {
         for (unsigned i = 0; i < num_children; i++) {
             m_children[i] = children[i];
             children[i]->inc_ref();
@@ -107,7 +107,7 @@ std::string const & sexpr::get_string() const {
 
 unsigned sexpr::get_num_children() const {
     SASSERT(is_composite());
-    return static_cast<sexpr_composite const *>(this)->m_num_chilren;
+    return static_cast<sexpr_composite const *>(this)->m_num_children;
 }
 
 sexpr * sexpr::get_child(unsigned idx) const {