strange compile problem (does not find emmintrin.h)

[josch09]

x86_64-pc-linux-gnu-gcc -I. -isystem include -march=core-avx2 -O2 -pipe -nostdinc -W -Wall -Wextra -Wchar-subscripts -Wmissing-prototypes -Wmissing-declarations -Wno-switch -Wno-unused -Wredundant-decls -fno-strict-aliasing -fno-stack-protector -Wa,--noexecstack -fpie -fvisibility=hidden -c x86_64/memccpy.c -o bin-x86_64/memccpy.o -D__dietlibc__
x86_64/memccpy.c:5:23: fatal error: emmintrin.h: No such file or directory
compilation terminated.

• the header file exists and is as part of the gcc-package installed:
  /usr/lib/gcc/x86_64-pc-linux-gnu/5.4.0/include/emmintrin.h
• due to the compilation settings I had to copy emmintrin.h, xmmintrin.h, mmintrin.h, mm_malloc.h from the gcc-include path to the local directory to make this file compile again, but I think this is not the intended way...