I've run into a similar problem now and here are the results from ldd and objdump as mentioned above:

$ ldd ~/SAP_RFC/INSTALL/lib/perl/5.10.1//auto/SAP/Rfc/Rfc.so
        linux-vdso.so.1 =>  (0x00007fff643df000)
        libm.so.6 => /lib/libm.so.6 (0x00007f0882898000)
        libdl.so.2 => /lib/libdl.so.2 (0x00007f0882694000)
        libpthread.so.0 => /lib/libpthread.so.0 (0x00007f0882477000)
        libc.so.6 => /lib/libc.so.6 (0x00007f0882115000)
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007f0881e01000)
        librfcum.so => ~/SAP_RFC/rfcsdk//lib/librfcum.so (0x00007f0881
+749000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f0882d36000)
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00007f0881533000)
        librt.so.1 => /lib/librt.so.1 (0x00007f088132b000)
[download]

$ objdump -tT ~/SAP_RFC/rfcsdk/lib/libsapu16.so | grep memsetU
0000000000008640 g     F .text  00000000000001c6              memsetU1
+6
00000000000089fc g     F .text  000000000000000a              memsetU
0000000000008640 g    DF .text  00000000000001c6  Base        memsetU1
+6
00000000000089fc g    DF .text  000000000000000a  Base        memsetU
[download]

$ objdump -ftT ~/SAP_RFC/rfcsdk/lib/* | grep 'file format\|memsetU'
~/SAP_RFC/rfcsdk/lib/libicudata.so.34:     file format elf64-x86-64
~/SAP_RFC/rfcsdk/lib/libicui18n.so.34:     file format elf64-x86-64
~/SAP_RFC/rfcsdk/lib/libicuuc.so.34:     file format elf64-x86-64
objdump: rfcilib.o: not a dynamic object
rfcilib.o:     file format elf64-x86-64
0000000000000000         *UND*  0000000000000000 memsetU16
objdump: cpictlib.o: not a dynamic object
cpictlib.o:     file format elf64-x86-64
00000000000057d0 g     F .text.hot      00000000000001c6 memsetU16
000000000005445e g     F .text.unlikely 000000000000000a memsetU
objdump: rsec4lib.o: not a dynamic object
objdump: rsec4lib.o:     file format elf64-x86-64
rscpa0lib.o: not a dynamic object
rscpa0lib.o:     file format elf64-x86-64
0000000000000000         *UND*  0000000000000000 memsetU16
objdump: rscpuc2lib.o: not a dynamic object
rscpuc2lib.o:     file format elf64-x86-64
~/SAP_RFC/rfcsdk/lib/librfcum.so:     file format elf64-x86-64
00000000001fecf0 l     F .text  00000000000001e3              memsetU1
+6
00000000001ec78e l     F .text  000000000000000a              memsetU
~/SAP_RFC/rfcsdk/lib/libsapu16_mt.so:     file format elf64-x86-64
0000000000008ba0 g     F .text  00000000000001e3              memsetU1
+6
0000000000008d97 g     F .text  000000000000000a              memsetU
0000000000008ba0 g    DF .text  00000000000001e3  Base        memsetU1
+6
0000000000008d97 g    DF .text  000000000000000a  Base        memsetU
~/SAP_RFC/rfcsdk/lib/libsapu16.so:     file format elf64-x86-64
0000000000008640 g     F .text  00000000000001c6              memsetU1
+6
00000000000089fc g     F .text  000000000000000a              memsetU
0000000000008640 g    DF .text  00000000000001c6  Base        memsetU1
+6
00000000000089fc g    DF .text  000000000000000a  Base        memsetU
~/SAP_RFC/rfcsdk/lib/libsapucum.so:     file format elf64-x86-64
0000000000038d90 g     F .text  00000000000001e3              memsetU1
+6
000000000002ce6e g     F .text  000000000000000a              memsetU
0000000000038d90 g    DF .text  00000000000001e3  libsapucum.so memset
+U16
000000000002ce6e g    DF .text  000000000000000a  libsapucum.so memset
+U
[download]