默认 ARMLIB
--libpath 可以指定.
手册上有描述:
The libraries are installed in subdirectories of the lib directory:

armlib
Contains the variants of the ARM C library, the floating-point arithmetic library (fplib), and the math library (mathlib).

cpplib
Contains the variants of the Rogue Wave C++ library (cpp_*) and supporting ARM C++ functions (cpprt_*), referred to collectively as the ARM C++ Libraries.

The accompanying header files for these libraries are installed in the inc directory.

The environment variable ARMCCnnLIB must be set to point to the lib directory, or if this variable is not set, ARMLIB. Alternatively, use the --libpath argument to the linker to identify the directory holding the library subdirectories. You must not identify the armlib and cpplib directories separately because this directory structure might change in future releases. The linker finds them from the location of lib.