only call Token::originalName() if necessary

[firewave]

this was causing Token::mOriginalName to be allocated for each Token even if it is empty.

[firewave]

before

63,297,945,427 (100.0%)  PROGRAM TOTALS
[...]
6,518,845,572 (10.30%)  build/token.cpp:Token::Match(Token const*, char const*, int) [/home/runner/work/cppcheck/cppcheck/cppcheck]
4,492,825,486 ( 7.10%)  ./malloc/./malloc/malloc.c:_int_malloc [/usr/lib/x86_64-linux-gnu/libc.so.6]
3,283,546,404 ( 5.19%)  ./malloc/./malloc/malloc.c:_int_free [/usr/lib/x86_64-linux-gnu/libc.so.6]
2,047,873,515 ( 3.24%)  build/library.cpp:Library::detectContainerInternal(Token const*, Library::DetectContainer, bool*, bool) const [/home/runner/work/cppcheck/cppcheck/cppcheck]
1,621,899,441 ( 2.56%)  ./malloc/./malloc/malloc.c:malloc [/usr/lib/x86_64-linux-gnu/libc.so.6]
1,497,750,449 ( 2.37%)  ./string/../sysdeps/x86_64/multiarch/memchr-avx2.S:__memchr_avx2 [/usr/lib/x86_64-linux-gnu/libc.so.6]
1,336,863,955 ( 2.11%)  ./string/../sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S:__memcmp_avx2_movbe [/usr/lib/x86_64-linux-gnu/libc.so.6]
  821,685,181 ( 1.30%)  ./malloc/./malloc/malloc.c:free [/usr/lib/x86_64-linux-gnu/libc.so.6]
[...]

after

61,862,521,835 (100.0%)  PROGRAM TOTALS
[...]
6,518,845,572 (10.54%)  build/token.cpp:Token::Match(Token const*, char const*, int) [/home/runner/work/cppcheck/cppcheck/cppcheck]
3,829,073,229 ( 6.19%)  ./malloc/./malloc/malloc.c:_int_malloc [/usr/lib/x86_64-linux-gnu/libc.so.6]
3,077,333,815 ( 4.97%)  ./malloc/./malloc/malloc.c:_int_free [/usr/lib/x86_64-linux-gnu/libc.so.6]
2,047,873,515 ( 3.31%)  build/library.cpp:Library::detectContainerInternal(Token const*, Library::DetectContainer, bool*, bool) const [/home/runner/work/cppcheck/cppcheck/cppcheck]
1,501,109,740 ( 2.43%)  ./malloc/./malloc/malloc.c:malloc [/usr/lib/x86_64-linux-gnu/libc.so.6]
1,497,752,982 ( 2.42%)  ./string/../sysdeps/x86_64/multiarch/memchr-avx2.S:__memchr_avx2 [/usr/lib/x86_64-linux-gnu/libc.so.6]
1,334,226,041 ( 2.16%)  ./string/../sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S:__memcmp_avx2_movbe [/usr/lib/x86_64-linux-gnu/libc.so.6]
  761,135,725 ( 1.23%)  ./malloc/./malloc/malloc.c:free [/usr/lib/x86_64-linux-gnu/libc.so.6]
[...]