Instrumented libraries: improve handling of custom patches.

third_party/instrumented_libraries/zlib1g.diff

Index: third_party/instrumented_libraries/zlib1g.diff
diff --git a/third_party/instrumented_libraries/zlib1g.diff b/third_party/instrumented_libraries/zlib1g.diff
deleted file mode 100644
index 18a6a3319b0f4df1c8458f61f41ad6532dce68e4..0000000000000000000000000000000000000000
--- a/third_party/instrumented_libraries/zlib1g.diff
+++ /dev/null
@@ -1,12 +0,0 @@
-diff -rupN ./configure ../zlib-1.2.3.4.dfsg-patched/configure
---- ./configure	2009-12-24 18:09:43.000000000 +0300
-+++ ../zlib-1.2.3.4.dfsg-patched/configure	2014-06-03 17:53:45.082074669 +0400
-@@ -72,6 +72,8 @@ cflags=${CFLAGS-"-O3"}
- # to force the asm version use: CFLAGS="-O3 -DASMV" ./configure
- case "$cc" in
-   *gcc*) gcc=1 ;;
-+  # Use the version script for clang builds as well.
-+  *clang*) gcc=1 ;;
- esac
- 
- if test "$gcc" -eq 1 && ($cc -c $cflags $test.c) 2>/dev/null; then