Fix esan compilation against glibc 2.26:

  /tmp/guix-build-clang-runtime-3.9.1.drv-0/compiler-rt-3.9.1.src/lib/esan/esan_sideline_linux.cpp: In static member function ‘static int __esan::SidelineThread::runSideline(void*)’:
  /tmp/guix-build-clang-runtime-3.9.1.drv-0/compiler-rt-3.9.1.src/lib/esan/esan_sideline_linux.cpp:73:22: error: aggregate ‘__esan::SidelineThread::runSideline(void*)::sigaltstack SigAltStack’ has incomplete type and cannot be defined

Patch from <https://github.com/google/sanitizers/issues/822>.

index d04f5909d..bc272dfe4 100644
--- a/lib/esan/esan_sideline_linux.cpp
+++ b/lib/esan/esan_sideline_linux.cpp
@@ -70,7 +70,7 @@ int SidelineThread::runSideline(void *Arg) {
 
   // Set up a signal handler on an alternate stack for safety.
   InternalScopedBuffer<char> StackMap(SigAltStackSize);
-  struct sigaltstack SigAltStack;
+  stack_t SigAltStack;
   SigAltStack.ss_sp = StackMap.data();
   SigAltStack.ss_size = SigAltStackSize;
   SigAltStack.ss_flags = 0;
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<div class='path'>path: <a href='/guix/log/?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/patches?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f&amp;showmsg=1'>patches</a>/<a href='/guix/log/gnu/packages/patches/netcdf-date-time.patch?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f&amp;showmsg=1'>netcdf-date-time.patch</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/patches/netcdf-date-time.patch?id=674dbeb43639db31c3f3a6e69ee7203296d0b50f'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2020-10-26 15:57:27 +0000'>2020-10-26</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/patches/netcdf-date-time.patch?id=a9291a28b233dba20a523da679bb446643abf977'>gnu: netcdf: Update to 4.7.4.</a></td><td>Christopher Baines</td></tr>
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This will fix an issue building qgis.

* gnu/packages/maths.scm (netcdf): Update to 4.7.4.
[source]: Remove the netcdf-tst_h_par.patch, also change the naming of the
source tarball, as the name seems to have changed for recent releases.
[inputs]: Update hdf5 and add curl.
* gnu/packages/patches/netcdf-tst_h_par.patch: Delete.
* gnu/local.mk (dist_patch_DATA): Remove deleted patch.


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