[libsigcpp] Fix usage in static build

[NancyLi1013]

Describe the pull request

• What does your PR fix?

  Fixes [libsigcpp-3] build failure #18808

  define SIGC_DLL as 1 only in dynamic build.

Note: No feature needs to test.

[ras0219-msft]

Thanks for the PR! This LGTM once my suggestion is applied.

[NancyLi1013]

The failures caused by libgo on x64-windows-static:

CMake Error at CMakeLists.txt:47 (configure_file):
  No such file or directory

Will be fixed via PR #19037

The failures caused by rxspencer on x86-windows:

D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(127): error C2059: syntax error: '>'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(127): error C2059: syntax error: ')'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(129): error C2059: syntax error: 'if'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(132): error C2059: syntax error: 'string'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(132): error C2143: syntax error: missing ')' before '->'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(132): error C2143: syntax error: missing '{' before '->'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(132): error C2059: syntax error: '->'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(132): error C2059: syntax error: ')'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(133): error C2059: syntax error: 'return'
D:\buildtrees\rxspencer\src\58e5a26934-bbc7804fdb.clean\regerror.c(134): error C2059: syntax error: '}'

May be fixed via PR #19039

The failures caused by pistache on x64-linux:

CMake Error at scripts/cmake/vcpkg_fixup_cmake_targets.cmake:95 (message):
  '/mnt/vcpkg-ci/packages/pistache_x64-linux/debug/lib/cmake/RapidJSON' does
  not exist.
Call Stack (most recent call first):
  ports/pistache/portfile.cmake:22 (vcpkg_fixup_cmake_targets)
  scripts/ports.cmake:140 (include)

Seems to be fixed via PR #18994

[NancyLi1013]

/azp run

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