Fix relative path bug in bibtex call.

Change-Id: I0d31786564320a6831259bcdf4c75a6b665c43ad

docs/CMakeLists.txt

diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
index 50de45d..b21a472 100644
--- a/docs/CMakeLists.txt
+++ b/docs/CMakeLists.txt
@@ -52,7 +52,7 @@
         -shell-escape ${CMAKE_BINARY_DIR}/docs/ceres-solver.tex
         -output-directory ${CMAKE_BINARY_DIR}/docs
         WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/docs
-    COMMAND ${BIBTEX_COMPILER} ${CMAKE_BINARY_DIR}/docs/ceres-solver.aux
+    COMMAND ${BIBTEX_COMPILER} ceres-solver.aux
     COMMAND ${PDFLATEX_COMPILER}
         -shell-escape ${CMAKE_BINARY_DIR}/docs/ceres-solver.tex
         -output-directory ${CMAKE_BINARY_DIR}/docs