With GCC 5.5:

make

cc -m64 -O3 -std=gnu11 -Wall -mpclmul -march=native -mfpmath=sse -mssse3 -fno-strict-aliasing -fno-strict-overflow -fwrapv -DAES=1 -DCOMMIT="2fd27cb0753c62e5766c86db28f2acc1d755547f" -D_GNU_SOURCE=1 -D_FILE_OFFSET_BITS=64 -iquote common -iquote . -c -MP -MD -MF dep/mtproto/mtproto-proxy.d -MQ objs/mtproto/mtproto-proxy.o -o objs/mtproto/mtproto-proxy.o mtproto/mtproto-proxy.c
cc: Warning: GCC option -mpclmul ignored. Suggest using -xarch=aes
cc: Warning: Option -mfpmath=sse passed to ld, if ld is invoked, ignored otherwise
cc: Warning: Option -fno-strict-overflow passed to ld, if ld is invoked, ignored otherwise
cc: Warning: Option -fwrapv passed to ld, if ld is invoked, ignored otherwise
cc: Warning: Option -quote passed to ld, if ld is invoked, ignored otherwise
cc: Warning: Option -quote passed to ld, if ld is invoked, ignored otherwise
cc: refused to overwrite input file by output file: objs/mtproto/mtproto-proxy.o
make: *** [Makefile:78: objs/mtproto/mtproto-proxy.o] Error 1

It seems as Makefile error.

Ah, I see. This is not portable code, will not build on Solaris in any way. Sorry and sadly.