libgit2.pc.in: also switch to LIB_INSTALL_DIR

b3237ac3 changed CMakeList.txt to use the more standard LIB_INSTALL_DIR
variable instead of INSTALL_LIB, but forgot to change libgit2.pc.in etc.
accordingly.

README.md

@@ -67,7 +67,7 @@ For more advanced use or questions about CMake please read <http://www.cmake.org
 The following CMake variables are declared:
 
 - `INSTALL_BIN`: Where to install binaries to.
-- `INSTALL_LIB`: Where to install libraries to.
+- `LIB_INSTALL_DIR`: Where to install libraries to.
 - `INSTALL_INC`: Where to install headers to.
 - `BUILD_SHARED_LIBS`: Build libgit2 as a Shared Library (defaults to ON)
 - `BUILD_CLAR`: Build [Clar](https://github.com/tanoku/clar)-based test suite (defaults to ON)

libgit2.pc.in

-libdir=@CMAKE_INSTALL_PREFIX@/@INSTALL_LIB@
+libdir=@CMAKE_INSTALL_PREFIX@/@LIB_INSTALL_DIR@
 includedir=@CMAKE_INSTALL_PREFIX@/@INSTALL_INC@
 
 Name: libgit2

packaging/rpm/libgit2.spec

@@ -65,7 +65,7 @@ to compile and develop applications that use libgit2.
 cmake . \
     -DCMAKE_C_FLAGS:STRING="%{optflags}" \
     -DCMAKE_INSTALL_PREFIX:PATH=%{_prefix} \
-    -DINSTALL_LIB:PATH=%{_libdir}
+    -DLIB_INSTALL_DIR:PATH=%{_libdir}S
 make %{?_smp_mflags}
 
 %install