Patch two Cppcheck bugs for upcoming GCC 13

Cppcheck does not compile with GCC 13 without these fixes, see:
https://gcc.gnu.org/gcc-13/porting_to.html

src/cppcheck-gcc13.patch

@@ -0,0 +1,18 @@
+GCC 13 has stricter allocator checks:
+https://gcc.gnu.org/gcc-13/porting_to.html
+
+Also, libstdc++ no longer leaks stdint.h definitions.
+--- a/lib/mathlib.cpp
++++ b/lib/mathlib.cpp
+@@ -25,2 +25,3 @@
+ #include <cmath>
++#include <cstdint>
+ #include <cstdlib>
+--- a/lib/smallvector.h
++++ b/lib/smallvector.h
+@@ -43,2 +43,5 @@
+     {}
++
++    template<class U> TaggedAllocator(const TaggedAllocator<U, N>);
++    template<class U> struct rebind { using other = TaggedAllocator<U, N>; };
+ };