build: cleanup configure script PKG_CHECK_MODULES

Cleanup the configure script package include lines.  There isn't a set
style for this yet, but this is an attempt to improve readability
whereas it's often one long line per library.  The CI will fail if there
aren't backslashes on lines for the AC_CHECK_HEADER.

Change-Id: I07be3e9c4ac7cd70a9e0d03299d25dcce6910cef
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/configure.ac b/configure.ac
index 667b88c..7fb93d5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -22,9 +22,21 @@
 LT_LIB_DLLOAD
 
 # Checks for libraries.
-PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging],, [AC_MSG_ERROR([Could not find phosphor-logging...openbmc/phosphor-logging package required])])
-AC_CHECK_HEADER([host-ipmid], [AC_MSG_ERROR(["phosphor-host-ipmid required and not found."])])
-AC_CHECK_HEADER(experimental/filesystem, ,[AC_MSG_ERROR([Could not find experimental/filesystem...libstdc++fs developement package required])])
+PKG_CHECK_MODULES(
+    [PHOSPHOR_LOGGING],
+    [phosphor-logging],
+    [],
+    [AC_MSG_ERROR([Could not find phosphor-logging...openbmc/phosphor-logging package required])]
+)
+AC_CHECK_HEADER(
+    [host-ipmid],
+    [AC_MSG_ERROR(["phosphor-host-ipmid required and not found."])]
+)
+AC_CHECK_HEADER(
+    experimental/filesystem,
+    [],
+    [AC_MSG_ERROR([Could not find experimental/filesystem...libstdc++fs developement package required])]
+)
 AX_PTHREAD([], [AC_MSG_ERROR(["pthread required and not found"])])
 
 # Check/set gtest specific functions.
@@ -39,7 +51,8 @@
 
 # Check for OECORE_TARGET_SYSROOT in the environment.
 AC_ARG_VAR(OECORE_TARGET_SYSROOT,
-    [Path to the OE SDK SYSROOT])
+    [Path to the OE SDK SYSROOT]
+)
 
 # Configure OESDK_TESTCASE_FLAGS environment variable, which will be later
 # used in test/Makefile.am