libhackrf: Add a pkgconfig .pc file to allow auto-discovery of prefix

Shamelessly copied from librtlsdr.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

host/libhackrf/CMakeLists.txt

@@ -43,6 +43,38 @@ include_directories(${LIBUSB_INCLUDE_DIR} ${THREADS_PTHREADS_INCLUDE_DIR})
 
 add_subdirectory(src)
 
+########################################################################
+# Create Pkg Config File
+########################################################################
+FOREACH(inc ${LIBUSB_INCLUDE_DIR})
+    LIST(APPEND HACKRF_PC_CFLAGS "-I${inc}")
+ENDFOREACH(inc)
+
+# use space-separation format for the pc file
+STRING(REPLACE ";" " " HACKRF_PC_CFLAGS "${HACKRF_PC_CFLAGS}")
+STRING(REPLACE ";" " " HACKRF_PC_LIBS "${HACKRF_PC_LIBS}")
+
+# unset these vars to avoid hard-coded paths to cross environment
+IF(CMAKE_CROSSCOMPILING)
+    UNSET(HACKRF_PC_CFLAGS)
+    UNSET(HACKRF_PC_LIBS)
+ENDIF(CMAKE_CROSSCOMPILING)
+
+set(prefix ${CMAKE_INSTALL_PREFIX})
+set(exec_prefix \${prefix})
+set(libdir \${exec_prefix}/lib)
+set(includedir \${prefix}/include)
+
+CONFIGURE_FILE(
+    ${CMAKE_CURRENT_SOURCE_DIR}/libhackrf.pc.in
+    ${CMAKE_CURRENT_BINARY_DIR}/libhackrf.pc
+@ONLY)
+
+INSTALL(
+    FILES ${CMAKE_CURRENT_BINARY_DIR}/libhackrf.pc
+    DESTINATION lib/pkgconfig
+)
+
 ########################################################################
 # Create uninstall target
 ########################################################################

host/libhackrf/libhackrf.pc.in

@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: HackRF Library
+Description: C Utility Library
+Version: @VERSION@
+Cflags: -I${includedir}/ @HACKRF_PC_CFLAGS@
+Libs: -L${libdir} -lhackrf
+Libs.private: @HACKRF_PC_LIBS@