I thought that I installed icu-staticlibs, but it seems that the build failed and I never noticed. I tried installing it again but it keeps giving me errors.
Here is the mess of output it gives me when I try to install if anyone is interested: Build icu-staticlibs-53.1-1 on Manjaro linux - Pastebin.com
Instead I followed the advice on this thread - thanks @Ross! - and commented out these lines:
# endif()
# set(Boost${CamelCaseComponent}Libs Boost${CamelCaseComponent} ${IconvLib})
# elseif(UNIX)
# if(BSD)
# find_library(IconvLib libiconv.a)
# if(NOT IconvLib)
# set(Msg "libiconv.a must be installed to a standard location.")
# set(Msg " For ${Msg} on FreeBSD 10 or later, run\n pkg install libiconv")
# message(FATAL_ERROR "${Msg}")
# endif()
# set(Boost${CamelCaseComponent}Libs Boost${CamelCaseComponent} ${IconvLib})
# elseif(NOT ANDROID_BUILD)
# find_library(Icui18nLib libicui18n.a)
# find_library(IcuucLib libicuuc.a)
# find_library(IcudataLib libicudata.a)
# if(NOT Icui18nLib OR NOT IcuucLib OR NOT IcudataLib)
# set(Msg "libicui18n.a, libicuuc.a & licudata.a must be installed to a standard location.")
# set(Msg " For ${Msg} on Ubuntu/Debian, run\n sudo apt-get install libicu-dev")
# message(FATAL_ERROR "${Msg}")
# endif()
# set(Boost${CamelCaseComponent}Libs Boost${CamelCaseComponent} ${Icui18nLib} ${IcuucLib} ${Ic$
# endif()
# else()
# set(Boost${CamelCaseComponent}Libs Boost${CamelCaseComponent})
# endif()
# endif()
It seems to be working now.