Add strtonum to compat library and export it

crypto library requires strtonum now, and add it to compat library.
remove it from applications compat/ directories.

apps/nc/CMakeLists.txt

@@ -29,14 +29,6 @@ else()
 	set(NC_SRC ${NC_SRC} compat/readpassphrase.c)
 endif()
 
-check_function_exists(strtonum HAVE_STRTONUM)
-if(HAVE_STRTONUM AND CMAKE_SYSTEM_NAME MATCHES "Darwin" AND
-    CMAKE_HOST_SYSTEM_VERSION VERSION_GREATER_EQUAL 20)
-	add_definitions(-DHAVE_STRTONUM)
-else()
-	set(NC_SRC ${NC_SRC} compat/strtonum.c)
-endif()
-
 if(NOT "${OPENSSLDIR}" STREQUAL "")
 	add_definitions(-DDEFAULT_CA_FILE=\"${OPENSSLDIR}/cert.pem\")
 else()

apps/nc/Makefile.am

@@ -43,8 +43,4 @@ if !HAVE_READPASSPHRASE
 nc_SOURCES += compat/readpassphrase.c
 endif
 
-if !HAVE_STRTONUM
-nc_SOURCES += compat/strtonum.c
-endif
-
 endif