libgit2 installation error

libgit2_error

Installing collected packages: cffi, pycparser
  Running setup.py install for cffi
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'libffi' found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'libffi' found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'libffi' found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'libffi' found
    Package libffi was not found in the pkg-config search path.
    Perhaps you should add the directory containing `libffi.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'libffi' found
    building '_cffi_backend' extension
    x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -DUSE__THREAD -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python2.7 -c c/_cffi_backend.c -o build/temp.linux-x86_64-2.7/c/_cffi_backend.o
    c/_cffi_backend.c:13:17: fatal error: ffi.h: No such file or directory
     #include <ffi.h>
                     ^
    compilation terminated.
    error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
    Complete output from command /usr/bin/python -c "import setuptools, tokenize;__file__='/tmp/pip_build_ravi/cffi/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-gaXk8k-record/install-record.txt --single-version-externally-managed --compile:
    Package libffi was not found in the pkg-config search path.

Perhaps you should add the directory containing `libffi.pc'

to the PKG_CONFIG_PATH environment variable

No package 'libffi' found

Package libffi was not found in the pkg-config search path.

Perhaps you should add the directory containing `libffi.pc'

to the PKG_CONFIG_PATH environment variable

No package 'libffi' found

Package libffi was not found in the pkg-config search path.

Perhaps you should add the directory containing `libffi.pc'

to the PKG_CONFIG_PATH environment variable

No package 'libffi' found

Package libffi was not found in the pkg-config search path.

Perhaps you should add the directory containing `libffi.pc'

to the PKG_CONFIG_PATH environment variable

No package 'libffi' found

Package libffi was not found in the pkg-config search path.

Perhaps you should add the directory containing `libffi.pc'

to the PKG_CONFIG_PATH environment variable

No package 'libffi' found

running install

running build

running build_py

creating build

creating build/lib.linux-x86_64-2.7

creating build/lib.linux-x86_64-2.7/cffi

copying cffi/lock.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/commontypes.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/cparser.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/ffiplatform.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/vengine_gen.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/__init__.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/api.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/model.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/verifier.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/backend_ctypes.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/gc_weakref.py -> build/lib.linux-x86_64-2.7/cffi

copying cffi/vengine_cpy.py -> build/lib.linux-x86_64-2.7/cffi

running build_ext

building '_cffi_backend' extension

creating build/temp.linux-x86_64-2.7

creating build/temp.linux-x86_64-2.7/c

x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -DUSE__THREAD -I/usr/include/ffi -I/usr/include/libffi -I/usr/include/python2.7 -c c/_cffi_backend.c -o build/temp.linux-x86_64-2.7/c/_cffi_backend.o

c/_cffi_backend.c:13:17: fatal error: ffi.h: No such file or directory

 #include <ffi.h>

                 ^

compilation terminated.

error: command 'x86_64-linux-gnu-gcc' failed with exit status 1